“A gleam of light is the dry soul, wisest and best.” (K 109; cp. D, R, S 118)
Heraclitus’ discussion of a wet versus the dry soul is somewhat reminiscent of early materialist teaching on the humors from Hippocrates (c. 460 – 377 BCE). Heraclitus certainly shared Hippocrates’ view that we are to understand everything using reason, not appealing to supernatural explanations; and he shared the view that our psyche itself can only be correctly understood only in reference to a material teaching of the elements.
Hippocrates’ later teaching is much more developed than the ideas hinted at in Heraclitus. For Hippocrates (or those who compiled the writings known under his name) “the four humors — blood, yellow bile, black bile and phlegm — …. could be correlated to the four primary qualities — hot, dry, cold and wet; to the four seasons, to the four ages of man (infancy, youth, adulthood and old age), to the four elements of (air, fire, earth and water), and the four tempraments” (Roy Porter, The Greatest Benefit to Mankind, p. 57).
Here Heraclitus simply correlates characters of the psyche or soul with the primary qualities and the elements. Soul, which is correlated to air, as that element that can become dry or moist (Cp. Robinson, p. 158), dies when becoming wet and is thought to be most alive when dry. The dryness, identified with aether (the “divine” air of the upper atmosphere), is identified with what is best in mankind. The best souls knows what is shared by all (F 30, 31; D 114, 113) and understands the unity of all things in logos (F 36; D 50).
Kahn, in agreement with Kirk, thinks there is a basic identity between this excellent state of the soul and the physical states where in these “are not merely put in one-to-one correspondence but are conceived as aspects of single reality; wisdom and excellence simply are the dry condition of the psyche” (K, p. 249).