Thales, who enjoyed great repute in his native city of Miletus and throughout Asia Minor at the commencement of the sixth century, calls water the beginning of all things. This was no new idea. For before his time poets had spoken of Oceanus, of the origin of the gods, and of the deluge from which the world was born anew. And the infinite sea could not but lie close to the thoughts of a seafaring nation. The novel and genuinely philosophic element in this proposition is rather the monistic endeavour to refer all phenomena to a single cause, to be sought not in heaven but on earth. For that which is taken as the beginning is not Oceanus, or, it may be, Poseidon, as in the older cosmogonies, but this palpable substance of water, out of which all things come and to which they all return. This original matter is indeed supposed to be animated by a divine spirit, but this divinity is not a person. There is no place for it on Olympus. Rather is it the expression of the immanent force which this philosopher recognised in the incomprehensible properties of the magnet, and there called “soul.” This enduing of nature with a soul is characteristic of the infancy of speculation, and hence this Ionic philosophy has also been called Hylozoism (the doctrine of living matter). The monistic impulse, which would bind the world and this single and supposed divine primeval force together, is diametrically opposed to the polytheistic tendency of the popular religion of Greece. Even in the first Greek philosophers this aspiration after unity points forward to monotheism, which was preached by Xenophanes, the Ionian, at the end of this same century. Of all the achievements of Thales his prediction of the eclipse of the sun (May 28, 585) is that which caused the greatest amazement, although its scientific significance is the most trifling of any. For, as the history of astronomy proves beyond controversy, Thales and his whole generation lacked the rudiments of knowledge necessary for the calculation of eclipses, and had not the faintest notion of how they came about. Hence he can only have employed according to a fixed method some such formula as the Chaldeans had gained from empiric observation in calculating their eclipse period of eighteen years and eleven days (_Saros_). The rule only suffices for approximate predictions. As a matter of fact, Herodotus, the earliest witness to this event, states that Thales allowed a margin of a whole year for the occurrence of the eclipse.