Beacon lights of science, a survey of human achievement from the earliest recorded times

Front matter

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Introduction

In the following pages the attempt has been made to sketch, in outline, the development of Science throughout the centuries, in the lives of those individuals who, in their time, have contributed notably to its progress. Naturally it has been impossible to include all who have taken some part in the great work. And also, many of the most promi¬ nent are still with us, their labors unfinished.

To the young man preparing himself for a scientific career, or entering upon its duties and obligations, the efforts of those thinkers and discoverers who have passed on and left to him the rich heritage of knowledge so far ac¬ cumulated should be an inspiration and an incentive. Or, taking a lower view of the matter, he should at least know enough of their lives to be able to connect the discoveries with the discoverers and to have some conception of their personality. We cannot be too mindful of the difficulties with which they had to contend in their explorations in a field of mystery, where none before them had blazed a path.

Doubtless there were true scientists before Euclid. But of them so little is certainly known, and with their dis¬ coveries so much of mysticism has been blended, that their stories come to us enveloped in a haze through which it is difficult to arrive at a fixed starting point. It is also hard to draw a line which shall clearly leave on one side the con¬ clusions of speculation, and on the other the logical deduc¬ tions from correctly observed phenomena. It seems clear, however, that the habit of collecting and classifying ob¬ served facts of nature (mainly astronomical) began with the Semitic people, and from them passed to the Aryans by way of that first intellectual flowering of its civilization, the Greeks. But the latter lived in an environment so beauti¬ ful, and possessed—probably as a result of it—a tempera-

VI

Introduction ment so aesthetic, that cold-blooded study of nature was un¬ congenial, and to all but a very few impossible. If the con¬ tents of the lost Alexandrian library could be restored in¬ tact and made accessible to the modern student, it would no doubt prove of surpassing interest, but probably also of little value to science.

As the glory of Greece faded under the stern shadow of Roman dominion, about all that the latter inherited from it, in the way of real knowledge, was the beginnings of the science of mathematics. Rome contributed practically noth¬ ing in its day to the explanation of natural phenomena, though it acquired a vast amount of empirical information through experience in dealing with its forces. And when, through the revival of mysticism, the Dark Ages came on, enveloping all Europe in their gloom, Science slumbered and dreamed for centuries, while Astrology and Alchemy wore its mask, and posed on the stage in the tinsel gar¬ ments of a dead and forgotten past.

It is difficult for us today to believe that in Europe, for more than a thousand years, the children who were born into the world were taught by their elders that there was but one true source of knowledge—religion—and that it was not only useless but impious to seek for the explanation of natural phenomena elsewhere. When at last revolt against this monstrous misconception began, Science awoke from its long sleep; at first—as before—in the form of a revival of interest in the fundamental branch of mathe¬ matics, which was quickly followed by renewed activity in astronomy and mechanics, the two departments whose manifestations were most readily open to observation.

Once recalled to life, other departments of knowledge be¬ came recognized in turn as they appeared as true children of science, and worthy descendants of those few masters among the ancients who, brushing aside as unworthy of their time the delights of speculation, devoted their energies to observation, and to the drawing of conclusions from the marshaling and classification of well demon¬ strated facts, rather than from the processes of ratiocina¬ tion. Yet the paths of these pioneers were beset with dif-

Introduction vu

Acuities. Copernicus was proclaimed a heretic by both of the grand divisions of the Christian church, Galileo was compelled to recant on his knees, and Darwin of a much later time was called an atheist, though all were men of deep religious feeling whose lives were full of love and re¬ spect for their fellows.

In arranging the order of these sketches, the life period has determined the sequence. With a few unimportant exceptions this brings to the reader in turn the different branches of knowledge as they were developed. Thus, with the exception of the early Greek studies in anatomy, mathe¬ matics, mechanics, and astronomy were the only sciences in existence up to the early years of the seventeenth century, when Mersenne, Harvey, and Gunter led the way with dis¬ coveries in acoustics, physiology, and magnetism. During the remainder of that period optics and physics were added. The eighteenth century witnessed the beginnings of the elec¬ trical, chemical, and geological sciences, and towards its close physiology and anatomy had become well founded on demonstrated facts.

In the nineteenth century all these departments of re¬ search were greatly developed, and chemistry, the science of matter, easily took first place in importance, with physics a close second, and philology, embryology, meteorology, anthropology, ethnology, pathology, biology, and a host of minor “ologies” crowding upo^i the stage from the wings and demanding recognition. Towards its end, physics, the science of energy, displaced chemistry in importance, and at the present time is well in advance, while the thinkers of the world are reaching out into the new fields of psycho¬ physics and psychology in the hope—and the expectation —of being able to solve with their aid some of the mysteries behind those concepts of matter and energy whose laws and manifestations are now fairly well understood, but whose causes still remain unexplained.

I. ANCIENT TIMES

PAGE

Thales ""Primitive Theories. 3

Anaximander —Mathematics . 4

Pythagoras Astronomy . 5

Empedocles -Evolution . 8

Democritus -Natural Science . 9

Hippocrates -Medicine . 11

Plato -Philosophy and Mathematics. 12

Aristotle -Natural Science . 14

Theophrastus Botany . 17

Erasistratus Anatomy. 18

Euclid Mathematics . 19

Archimedes Mechanics. 21

Eratosthenes Astronomy .. i. 23

Aristarchus Astronomy . 24

Apollonius —Mathematics . 26

Hipparchus Astronomy . 27

Dioscorides Botany . 29

* Ptolemy Cosmology and Geography. 30

Galen Anatomy. 33

Piophantus Mathematics . 35

II. THE MIDDLE AGES

Aryabhatta ""Astronomy . 41

Brahmagupta “Mathematics . 42

Al Khuwarismi- Mathematics. 43

Al Hazen -Mathematics. 45

Bhaskara - Mathematics. 46

Bacon Speculative Philosophy and Natural Science.. 48

Peuerbach Mathematics. 52

Muller (Eegio- Mathematics. 53

montanus)

Da Vinci General Science . 56

Copernicus Astronomy . 58

Fallopius Anatomy. 62

IX

X

111 . THE SIXTEENTH CENTUEY

PAGE

Tartaglia Mathematics. 67

Yes alius "-Anatomy. 68

Gesner -^Natural History . 70

Eustacio Anatomy. 71

Fabrizio Anatomy. 72

Gilbert "-Natural Science . 74

Brahe Astronomy . 76

Stevin Mathematics. 82

Napier Mathematics. S3

Galileo Astronomy . 85

Kepler Astronomy . 94

Harvey Physiology . 99

Mersenne Physics . 101

Desargues Mathematics. 103

Descartes Mathematics. 104

IV. THE SEVENTEENTH CENTUEY

Fermat

Mathematics.

Guericke

Physics.

Torricelli

Physics.

Pascal

Mathematics.

Boyle

Chemistry.

Cassini

Astronomy .

Malpighi

Anatomy.

Huygens

Physics.

Leeuwenhoek

Microscopy.

Hooke

Physics.

Newton

Physics.

Boemer

Physics.

Leibnitz

Halley

Mathematics and Philosophy...

Astronomy .

Bradley

Astronomy .

Maclaurin

Mathematics.

De Jussieu

Botany.

V. THE EIGHTEENTH CENTUEY

Gray

Chemistry.

Bernouilli

Mathematics.

Franklin

Electricity .

Buffon

Natural History ...

Dinnaeus

Natural History .

xi

PAGE

Euler Mathematics. 154

Clairault Physics . 156

D’Alembert Mathematics. 158

Hutton Geology. 160

Hunter "Physiology and Anatomy. 161

Black Chemistry. 162

Spellanzani -Physiology . 164

Cavendish Chemistry. 166

Priestley Chemistry. 167

Coulomb Physics . 169

-Watt "Mechanics. 171

Lagrange Physics . 173

Galvani Anatomy. 174

Herschel Astronomy . 175

Scheele Chemistry. 177

Hauy Mineralogy. 179

.Lavoisier Chemistry. 181

Lamarck Natural History . 182

Volta Electro-Chemistry. 184

Charles Aeronautics . 186

Monge Mathematics. 188

Bode Astronomy . 190

Werner Geology. 192

Berthollet Chemistry. 193

-Jenner Physiology . 195

Laplace Astronomy . 198

Legendre Mathematics. 200

Rumford Physics. 202

Proust Chemistry. 204

Prony Mathematics. 205

Chladni Physics. 207

Wollaston Chemistry. 209

Dalton Chemistry. 211

Cuvier Anatomy. 213

Humboldt Natural History . 215

Oersted Physics. 217

Brown Botany . 219

Young Physics. 221

Bell Anatomy. 222

Ampere Electricity . 223

Avogadro Physics. 225

Gauss Astronomy . 229

Davy Chemistry. 231

Gay-Lussac Chemistry. 232

Berzelius Chemistry. 234

Silliman Geology. 235 xii Contents

PAGE

Audubon -Natural History . 237

Brewster Physics. 239

Bessel Astronomy . 241

Dulong Chemistry. 242

Chevreul Chemistry. 243

Arago Astronomy . 245

Fraunhofer Physics. 247

V Ohm Electricity . 248

Fresnel Physics 250

Daguerre —Photography . 251

Faraday Electricity . 253

Yon Baer Embryology. 255

Lobatchevsky Mathematics. 258

Weber Physiology . 259

Sadi-Carnot Physics. 261

Lyell -Geology. 263

Henry • Electricity . 264

VI. THE NINETEENTH AND TWENTIETH CENTURIES

Dumas Chemistry. 269

Wohler Chemistry. 271

Muller Physiology . 273

Abel Mathematics. 275

Wheatstone ' Physics. 277

Doppler Physics. 278

Liebig Chemistry. 279

Maury Geography .... 281

'—Agassiz Geology. 282

Guyot Geography . 284

Darwin Biology . 286

Forbes Physics. 287

Gray Botany . 289

Andrews Chemistry.. 291

Draper Chemistry. 293

Leverrier Astronomy . 294

Bunsen Chemistry. 295

Pacini Physiology . 297

Dana Natural History . 298

Bernard Physiology . 300

Yon Mayer Physics. 301

Angstrom Physics. 303

Hooker Botany . 306

Joule Physics. 307

Foucault Physics. 309 xiii

PA6E

Adams Astronomy . 310

Stokes - Physics. 311

Tyndall Physics . 313

MtiLLER Biology. 315

Helmholtz Physics. 316

Virchow “-Pathology. 318

Galton -Biology and Physics. 320

Wallace —Natural History . 321

Mendel Biology. 324

Clausius Physics. 325

Pasteur Bacteriology . 327

Leidy Natural History . 328

Fabre Natural History .«-331

Hittorf Physics. 334

Kirchoff Physics. 336

Thomson Physics . 337

Broca Anatomy. 339

Huggins Astronomy . 340

Schulze Biology . 342

Bates Natural History . 343

Huxley Biology. 345

Buckland Natural History . 347

Berthelot Chemistry. 349

Lister Medicine. 351

Kekul 6 Chemistry. 353

Marsh Natural History . 354

Maxwell Physics . 357

Tylor Biology. 358

Crookes Physics. 360

Nobel High Explosives . 362

‘Lubbock Natural History . 364

Weismann Zoology. 365

Langley Aviation . 367

Mendeleef Chemistry. 368

Haeckel Evolution . 370

Newcomb Mathematics. 371

Lockyer Astronomy . 373

Hill Astronomy ... 375

Perkin Chemistry. 377

Abbe Meteorology . 380

Gibbs Mathematics . 381

Cope - Natural History . 383

Kovalevsky Embryology . 385

Bayleigh Physics. 386

Dewar Physics. 388

Koch Bacteriology. 390 xiv

PACE

Michel-Ijevy Geology. 392

Boltzmann Physics. 394

Metchnikoff Biology . 396

Wroblewski x Physics. 397

Roentgen Physics. 399

Edison Electricity . 400

Rowland Physics. 403

Moissan Chemistry. 405

Fischer Chemistry. 406

Ramsay Chemistry. 408

Becquerel -Physics. 411

Van't Hoff Chemistry. 412

Thomson Electricity . 414

Hertz Physics. 416

Arrhenius Chemistry. 418

Bragg Physics. 420

Zeeman Physics. 422

Steinmetz Electricity . 423

Curie Chemistry. 426

Marconi Electricity . 430

Einstein Physics. 432

Index . 437

ILLUSTRATIONS

“The Founders of Science”

The above is the caption of a series of bas-relief portraits in bronze decorating the new million-dollar building of the National Academy of Sciences and the National Research Council, in Washington, D. C. Thirty-seven world scientists were chosen, only two of whom were American.

Hippocrates, Aristotle, Archimedes, Copernicus, Vesalius, Harvey . Frontispiece

PAGE

Galileo, Leonardo, Hipparchus, Euclid, Democritus, Thales . 70

Carnot, Bernard, Joule, Pasteur, Mendel, Maxwell.... 140

Humboldt, Dalton, Lamarck, Watt, Franklin, Huygens. 210

Descartes, Newton, Linnaeus, Lavoisier, Laplace, Cuvier, Gauss. 290

Galton, Gibbs, Helmholtz, Darwin, Lyell, Faraday

I

For the purpose of this volume it will be convenient to define its first department (Ancient Times), as the epoch extending from the beginnings of recorded human history, up to the fall of the Roman Empire in the year 476 of the present era, a period covering certainly 6000 years; for inscriptions that are clearly alphabetical in their character appear on many of the Egyptian and Chaldean monuments, whose age has been determined as early in the 5th millennium b.c. And before them for an unknown time were the years of hieroglyphs.

But we may safely deduct at once at least four millenniums from this reckoning, as a period during which the art of writing was confined wholly within the priestly class, and employed only to record the principal acts of rulers, or startling occurrences like famines, floods, eclipses, etc. And about as safely another thou¬ sand, for the slow development of a script convenient enough in execution, to permit of the recording of conclusions arrived at by observers of those natural phenomena that were daily presented to the senses and minds of the civilized people among the ancients. This brings us down to a date somewhere between 750 b.c. and 500 b.c., at which time appeared Thales of Miletus, the first of whose story enough is known to warrant his inclusion in a list of scientists—that is, of collectors and classifiers of observed phenomena’, apparent or real. Certainly there were students and scholars before his day, for by then much true knowledge of various kinds had accumulated, but their names and their histories have been lost.

During the eleven hundred years remaining of the period, namely, from 624 b.c. to 476 a.d., history has preserved less than a score of names worthy of enrollment as 11 Beacon Lights of Science. ’ 7 It is a significant fact that, of the total number, sixteen belonged to the Greek race, the other two, Thales and Ptolemy, being re¬ spectively of Plioenecian and Egyptian ancestry or birth. And, as showing the versatility of Hellenic culture, four of these attained eminence in mathematics, four in astronomy, two each in botany and the healing art, one each in general philosophy, mechanics and anatomy, while to Empedocles must be accorded the supreme honor of having formulated the first known conception of the theory of evolution.

THALES (circa 624-560 b.c.)

PRIMITIVE THEORIES

Thales is reputed to have been a native of Miletus, a very famous ancient Greek city located on the western coast of Asia Minor at the mouth of the Maeander river. By race he was of Phoenecian ancestry. He seems to have been possessed of engineering capacity, for he was en¬ gaged to construct an embankment along a portion of the shores of the river Halys.. He was also a merchant of importance, and traveled extensively, particularly in Egypt, where he became familiar with such astronomical and mathematical knowledge as by then had accumulated among the priesthood. In consequence, upon his return to Miletus, he was able to predict an eclipse of the sun, which actually occurred in the year 585 b.c., and acquired thereby a great reputation. Being a man of wealth and leisure he decided to devote the balance of his life to philosophy, and was regarded either then or later, as one of the six or seven wise men of ancient Greece.

He taught that the fundamental element of which all things was composed was water. That the earth floated upon it; that it was the cause of earthquakes and volcanos; that it was the main component of all vegetation—which apparently could not exist without it; of all animal life that lived on vegetable food, and hence by necessity, of all flesh-eating animals, including man. According to some of his commentators he regarded earth (soil and rocks), air and fire as also of elementary character, though of secondary importance. He is credited with having be¬ lieved that the earth was of the form of a sphere, and that the year consisted of exactly 365 days. He expressed his views in words only and committed nothing to writing.

Thales, whether a real or a legendary character, repre¬ sents the beginnings of Greek intellectual life. Before his day much information about the ordinary phenomena of life had been gathered in Egypt, Chaldea, Phoenecia, and to a lesser extent in India and China. But life was hard and unlovely among all those people, for they occupied regions where climatic conditions were severe, and the struggle for existence a pitiful one, except for the favored few. To the Greeks, however, had been given a pleasanter homeland, a more genial climate, and an environment that encouraged thoughtfulness and a desire to understand the causes of things. As their civilization advanced, a very considerable percentage of the mass of the population lived in comfort and comparative luxury. Out of such condi¬ tions arise appreciation of the beauties of nature, and a desire to produce beautiful things, in other words, the fine arts. Also a tendency to speculate about the mysteries of life and the universe, but without any observational foundation. These were the impelling and prevailing ten¬ dencies in Grecian life until the time of Aristotle (about 350 b.c) , who taught a more correct way of looking at things.

ANAXIMANDER (610-546 b.c.)

Anaximander was bom at Miletus, one of the populous and famous ancient cities of the western coast of Asia Minor. Very little is known of his personal history be¬ yond the fact that he became, after the death of the philosopher Thales, the head of the Ionian school of Greek thought. Aside from the reputation which this position brought to him, he is generally credited with having been the first among the ancients to proclaim that the axis of the earth must be inclined to the extent of about 23 degrees to the plane in which it stood (or moved) with respect to the sun. In other words, he taught as a fact the phenome¬ non we now call the obliquity of the ecliptic. Yet there is no clear evidence that he had any true conception of the shape of the earth, of its revolution on its own axis, or of its annual journey around the sun. Yet he is believed to have been the inventor of those old astronomical de¬ vices the gnomon and the polos. The views of the cosmos held in his day were full of strange contradictions. It is difficult to believe that a mind capable of reaching so close an approximation to the cause of the annual change of seasons, and of producing an instrument capable of indicating divisions of time by the changing positions of the shadow it cast, could have been wholly unacquainted with the causes behind these results. But, as was the case with most, if not all of the Greek philosophers, Anaxi¬ mander seems to have held and taught, along with a few correct facts of Nature, many others that now seem ab¬ surd. For instance, his conception of the Universe appears to have been that of at least three concentric transparent and revolving cylinders, to the outer one of which the sun was firmly fixed, while the middle one carried the moon, and the innermost one the stars. Within these was the earth, also cylindrical in form, and either stationary or moving with the others. He was uncertain as to the posi¬ tion of the five planets then known. On the other hand, according to some of the ancient writings, he made some excellent approximations of their size and relative dis¬ tances from each other.

PYTHAGORAS (c. 580-500 b.c.)

Such accounts as have come down to us of the life and activities of this traditionally famous Greek, are not at all clear, and much is plainly pure myth. He appears to have been a native of Samos, an island off the west coast of Asia Minor; but of his ancestry and of his youthful years we have no reliable information. In his early ma¬ turity he appeared in the city of Cretona, in the southern part of Italy, which at the time was the seat of a Grecian colony. Here he founded a society or brotherhood, of the nature of an intellectual autocracy, which later took on a political cast, and became deeply involved in the fierce struggles then in progress throughout the Grecian world between democracy and plutocracy. In the end the few Pythagoreans who survived were driven from the country. It is not known whether Pythagoras escaped before the culmination of this event, or perished in it. Whichever was the case, Pythagorism represented subsequently some very strange conceptions of the Universe, which have come to us through contemporaneous and subsequent writers, but so alloyed with fable and nonsense that students of Grecian history and thought have found it very difficult to decide with any degree of certainty much more than the outline of his teachings. Not a word that could be safely ascribed to him personally has been preserved, and of the writings of his disciples we have only fragmentary re¬ mains. From these, and from later writers, two of the more startling of the tenets of the cult appear to have been as follows:

As to the substance of the world, they conceived it to be composed of material atoms, each one of which was so infinitesimally minute as to represent position only, without size. Two, side by side, expressed a line and conveyed the idea of direction, but again without magnitude. Three (one being at right angles to the other two) ' indicated surface, but without thickness, thus being merely the rep¬ resentation of area or extension; while four (the fourth at right angles to the other three) constituted a solid, or the conception of Form. Thus the three-dimensional prop¬ erty of Space was reached and explained. It was regarded as unlimited in extent, and filled with air, or, according to others, a void. As to the atom, if it were of earthy matter it was believed to possess the shape of a cube; if of fire, that of a tetrahedron or three-sided solid; if of water, that of an icosahedron or twenty-sided figure, while those of all other substances were twelve-sided masses. Out of all this rubbish the only item of importance is the conception of the atom as the ultimate component of mat¬ ter.

In regard to the external Universe, the Pythagoreans taught that at its center there was a source of light and heat in the shape of a perpetual and intense fire, and that all the heavenly bodies—including the earth—revolved around this in concentric circles at various distances apart. That the earth was the nearest to this source, and made its revolution in such a way that one of its hemispheres always faced this source (just as one face of the moon only is presented to the earth), and was necessarily uninhabit¬ able, on account of its intense heat. All the other celestial bodies shone by reflected light only, the earth obtaining its share by reflection from the largest of them, the sun. When the earth is on the same side of the central fire as the sun the phenomenon of daylight exists. When it is on the opposite side, that of night supervenes.

These examples of Pythagorean philosophy are suffi¬ cient to show that its founder and his disciples were people gifted with vigorous imaginations, but poorly equipped with demonstrated facts; just such a combination as might have been expected of the lively and speculative Greek mind at that age of the world; so different in its nature from that of the still older Egyptians and Babylonians, each of whom developed theories of the Universe of a very different kind.

Whether Pythagoras ever existed as an individual, or whether the name simply stands for a system of philosophy having for its object to account for the innumerable mys¬ teries of existence, the cult very properly takes its place among the beginnings of science for, in spite of the mass of error it stood for, here and there appear conceptions and conclusions that have since been demonstrated as re¬ alities.

EMPEDOCLES (495-435 B.C.)

EVOLUTION

This Greek philosopher was bom of a distinguished fam¬ ily whose home was in the city of Agrigentum in Sicily, when that island was a Grecian colony. In addition to having attained a high standing as a physician, he is re¬ garded as one of the notable philosophers of the ancients. He also appears to have been a strong advocate of certain political doctrines of a democratic tendency, which he en¬ deavored to put in practice in his native city. Very little reliable information of his life has been preserved, but many marvelous stories have come down to us relating to his beliefs and ideas, and to his powers as a physician. The most of these are simply exaggeration, though perhaps based on real facts of a less startling nature. Of the manner of his death several tales are told. The most com¬ mon was to the effect that he leaped into the crater of Mt. Aetna. Another states that he experienced translation, after the manner of the Jewish prophet Elijah. He is said to have performed several miracles, one of which was to bring back to life a young girl long dead; and another to avert from Sicily a pestilence raging in southern Italy, by compelling a change in the direction from which the wind was blowing.

Amid all this legendary nonsense it seems to be a fact that he was one of those early thinkers who had grasped some germs of the idea of evolution, in his endeavor to account for the mysterious phenomena of the Universe. Aristotle was another. With Empedocles the theory took form in the saying that “Nature produces those things which, being continually moved by a certain principle contained in themselves, arrive at a certain end.” To connect the rather obscure meaning of this sentence with the modern doctrine of evolution requires some knowledge of the brand of philosophy he represented. He held that “Being,” by which he meant Matter, was eternal and im¬ perishable. He considered it to be of four kinds or elements mutually independent, namely, earth, air, fire and water. He maintained the existence of two fundamental and opposing forces, which he typified as Friendship and Strife; the first of which was the indwelling and normal principle, and the second the external and abnormal one. These two, in their perpetual conflict, the one to maintain the status quo and the other to change it, produced all the phenomena of nature. He held that these changes were constantly and imperceptibly occurring, and had been throughout unknown ages in the past, with the effect of steady progress upward in all phases of existence. Finally, that man was, at the present, the highest product of the process. In thus indicating that the principle he called Strife—by which perhaps he intended to convey the idea of competition for existence or supremacy—was always in the end victorious, he may have grasped the germ of the idea at the foundation of Darwinianism, the survival of the fittest. With Empedocles chance, or acci¬ dent was the cause of the successes of Strife over Friend¬ ship. Aristotle rejected this as of the nature of an impiety.

DEMOCRITUS (circa 470-400 b.c.)

NATURAL SCIENCE

This notable Greek, whose birthplace was the ancient town of Abdara in Thrace, went by the name of “The Smiling Philosopher 9 ’ among his intimates, because of the geniality of his disposition and his optimistic temperament. About all that is known of the details of his life is that he was a man of high moral character and strong religious tendencies, was well educated according to the standards of the time, was deeply interested in mathematics and astronomy, wrote extensively on these subjects and on philosophy, and had traveled through much of the civilized world of his day. Only fragments of his writings have been preserved. These were collected and published by Mullach in Berlin in 1843. From them, aided by references in, and commentaries by other writers—both Greek and Latin, it has been possible to deduce the general system of philoso¬ phy which he held, and probably taught.

It was based on a theory of that aspect of matter which the mind receives from the five senses, the essential nature of which has been considered, until recently as unknowable; but which now seems to have been resolved into one of the manifestations of the equally unknowable entity we call Energy. In his system a material atom was postulated, infinite in multitude, not all of one size or kind, but each endowed with the power of motion, and the ability to unite into aggregates of all dimensions, forms and quantities, under certain pre-ordained laws; some of which eventuated in the phenomenon of life, and others in static con¬ ditions, which were apparent in those manifestations like rocks and metals, which plainly lacked the vital quality. For these reasons his philosophy was known among the Greeks as the Atomic System. To Democritus therefore belongs the credit of having first conceived the idea of the material atom.

To what the theory led, and what speculative structure he reared upon its foundation, is not clear. He denied the existence of Design in the Cosmos, but asserted that of immutable law. Animals, vegetation, moving air and water, he regarded as combinations of atoms of average quality. Consciousness and thought the product of the coming to¬ gether of particles of a finer kind. And he postulated the existence of a third and superior class, of which the sub¬ stance of the High Gods was composed. Happiness he considered as the supreme object of existence. To attain it, the passions must be controlled, and temperance made the rule in all departments of life. As to a possible future stage of being, he seems to have had no theory.

It is thought by some students of the Greek mind that Epicurus (circa 324-270 b.c.) was a believer in his philos¬ ophy, and taught it, with probably some amplifications of his own. According to him, fear of the Gods and fear of death were the two great destroyers of human happiness, and the main objects in life were to overcome these terrors, by rising superior to them. Believing that Personality ended with death, he argued against looking to the future for any amelioration of present condition; insisted that life was wholly an affair of to-day, that it was beautiful, that it was the summit of wisdom to enjoy its gifts as they came, but always temperately, and with consideration for others. He thought that the gods were imperishable, and could have nothing to do with us, inasmuch as they lived on a different plane. If these were also the ideas of Democritus, they were rather above the average of the time, but have little value for the present.