The beginnings of Physical Science

The earliest literary survivals from the Greek world, the epic poems of Homer and Hesiod, contain, inter alia, accounts of natural phenomena and of the origins of the universe. But the latter are speculative mythology, while the former invariably impute large-scale natural phenomena to supernatural forces: Zeus coruscates miscreants with thunderbolts; Poseidon shakes the earth in anger; Apollo visits plagues upon the impious. There is no attempt to explain events in naturalistic terms (that is, as the natural result of natural forces and the intrinsic properties of things), and no effort to reduce the apparent diversity of phenomena to a small set of explanatory concepts in terms of which they are to be accounted for.

The Greeks themselves considered that with Thales (fl. c.585 BC) there emerged a wholly new way of looking at things, one characterized by Aristotle as the search for the archai, or basic ‘principles’ of things. According to tradition, Thales, the first of the so-called Presocratics, made water his archē. Water was fundamental to the world and its processes, perhaps, as Aristotle says, because of the observation that moisture is necessary for life and that ‘heat comes from moisture’; moreover, the earth ‘rests on water’, a feature which accounts both for its general stability, and also (probably) for the occasional earthquake. Thales also claimed that magnets possess souls, presumably because they have that power to induce motion which is characteristic of animate life.