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THALES is commemorated as the initiator of abstract thought, scientific and philosophic. In his time, and through his teaching, there first began the use of a true scientific method. For it may be said that he first employed abstract reasoning in investigation, and first taught that natural phenomena must have natural causes.
He was born of a noble family of Miletus, the greatest of the twelve Ionian cities. Honours and wealth were within his reach, but he sacrificed them that he might give himself to a life of contemplation. Yet he became no mere recluse. So high stood his reputation for practical sagacity, the fruit of a life of over ninety years, that he was accounted the greatest of the Seven Wise Men, his pithy sayings were treasured up, and it was still remembered in Herodotus' time how he had perceived that the only hope of maintaining the independence of the Ionians lay in a real federation of their cities.
Hitherto the search for knowledge had gone little beyond the immediate needs of life. The natural desire for some explanation of the universe had been satisfied by mythology, and men had rested content in the belief that the lightning, the eclipse, and the storm were manifestations of the gods. A new era opened in the history of thought when Thales, finding his experience in conflict with the old poetic fictions, faced the problem once more. He saw that no one called in a deity to explain the simple facts of everyday life, where the natural causes are obvious. He saw, too, that as one's knowledge grows, natural causes come to light which were before unseen. Might there not, then, be some natural cause for all phenomena whatsoever? Thus he was led to speculate on the origin and growth of the universe. His experience told him that matter may assume different forms; and he reasoned, as we may suppose, that when a new thing is formed it cannot contain any substance which did not exist before. The polytheistic dogma of Metamorphoses had already made him familiar with a wider view of the same conception; so that he allowed himself to pass from the seen to the unseen, and to feel that beneath the diversity of the world there is in all things some common substance or principle from which by natural means they develop. Such a substance he saw in water or moisture, a thing essential to life, and, as it seemed to him, absolutely simple in character. From the first there was latent in it a power of change and development whereby it transforms itself into all the variety of the universe.
But these general or philosophic speculations, dealing with problems far beyond his competence to solve, could lead to no definite result, and are of interest chiefly as indicating a new epoch in the history of human thought. Of more permanent value were his researches in positive science. The search for an original principle explanatory of the universe went side by side with the process of analysis, the resolution of complex wholes into their simplest elements, the abstraction of these last, and the discovery in them of uniform law. Thales is said to have taught geometry to the priests of Thebes. Others have maintained that he learnt it from them. We know now that Egyptian geometry was limited to special figures and volumes. To Thales and his followers is due the geometry of the lines which bound them; a conception which gave an impulse to science comparable to that which the introduction of alphabetic characters gave to intellectual efforts generally. The two discoveries associated with his name are (1) that the sum of the angles of a triangle are equal to two right angles: and (2) that the sides of similar triangles are proportional; to which may be added the conception of geometrical loci.
The first result of the new geometry was the reconstitution of Astronomy; which though still dependent on graphic methods, advanced from mechanical representation of the heavenly bodies to diagrams. Lastly, the dogma of Metamorphoses became in Thales' hands a real preparation for the theory of atoms; in this direction the line from him to Democritus is unbroken. As special sciences developed, the belief in the unity of Nature was gradually abandoned; yet was still retained in the modified form of Aristotle's theory of the four elements. But the fame of Thales will rest mainly on his mathematical discoveries. He founded the geometry of lines: his two problems laid the foundation of algebra by instituting respectively an equation and a proportion: and he thus introduced the first type of a natural law, i.e. the expression of a fixed dependence between varying quantities; the disentaglement of constancy in the midst of change.
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| This biography is
reprinted from The New Calendar of Great Men. Ed. Frederic
Harrison. London: Macmillan and Co., 1920. |
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