The thought traced that it is the ‘fluid’ in which life is and by which life is generated not only appears from Homer onwards in the recognition and worship of rivers as the generative powers (see pp. 229 ff.), but it also has its cosmic correlate. For Homer the ‘generation’ (γένεσις) ‘of all’ (πάντεσσι) is the river ʾωκεανός (Okeanos) which surrounds the earth and is associated with ‘mother Tethys’. τὸ γὰρ ὕδωρ πάντων ἠ зωή says the scholiast, which reminds us of the concept of αἰών above. γένεσις suggests the process or, in this context, the substance rather than the agent of generation. That Homer uses it twice of the cosmic river and not elsewhere of gods, men, or animals, which are agents, ‘fathers’, can scarcely be accidental. In the body it is, we have seen, the sources of generation for which men feel awe and by which they swear. Thus perhaps (cf. ἠνορέην on p. 246) we can better understand why the ‘greatest and most awful oath for the blessed gods’ is by the water of the river of the underworld, the water of Styx proper to the dead.

If such beliefs were current and traditional, we might expect them to be the starting-point of the earliest (Ionian) ‘philosophers’ in their views of ϕύσις or, as Plato interprets, γένεσις, ‘generation’, in their discussions of the primary substance from which all developed.