That "nothing comes into being out of nothing, and that nothing passes away into nothing," was the conviction with which he and those who followed him started on their quest. All around was change; everything always becoming something else; "all in motion like streams." There must be that which is the vehicle of all the changes, and of all the motions which produce them. _What_, therefore, was this permanent and primary substance? in other words, of what is the world made? And Thales, perhaps through observing that it could become vaporous, liquid, and solid in turn; perhaps--if, as tradition records, he visited Egypt--through watching the wonder-working, life-giving Nile; perhaps as doubtless sharing the current belief in an ocean-washed earth, said that the primary substance was WATER. Anaximander, his friend and pupil, disagreeing with what seemed to him a too concrete answer, argued, in more abstract fashion, that "the material cause and first element of things was the Infinite." This material cause, which he was the first thus to name, "is neither water nor any other of what are now called the _elements_" (we quote from Theophrastus, the famous pupil of Aristotle, born at Eresus in Lesbos, 371 B. C.). Perhaps, following Professor Burnet's able guidance through the complexities of definitions, the term BOUNDLESS best expresses the "one eternal, indestructible substance out of which everything arises, and into which everything once more returns"; in other words, the exhaustless stock of matter from which the waste of existence is being continually made good. Anaximander was the first to assert the origin of life from the non-living, i. e., "the moist element as it was evaporated by the sun," and to speak of man as "like another animal, namely, a fish, in the beginning." This looks well-nigh akin to prevision of the mutability of species, and of what modern biology has proved concerning the marine ancestry of the highest animals, although it is one of many ancient speculations as to the origin of life in slimy matter. And when Anaximander adds that "while other animals quickly find food for themselves, man alone requires a prolonged period of suckling," he anticipates the modern explanation of the origin of the rudimentary family through the development of the social instincts and affections. The lengthening of the period of infancy involves dependence on the parents, and evolves the sympathy which lies at the base of social relations. (Cf. Fiske's Outlines of Cosmic Philosophy, vol. ii, pp. 344, 360.)