Further, just as summer and winter are one, and necessarily reproduce one another by their “opposite tension,” so do life and death. They, too, are one, we are told; and so are youth and age (fr. 78). It follows that the soul will be now living and now dead; that it will only turn to fire or water, as the case may be, to recommence once more its unceasing upward and downward path. The soul that has died from excess of moisture sinks down to earth; but from the earth comes water, and from water is once more exhaled a soul (fr. 68). So, too, we are told (fr. 67) that gods and men are really one. They live each others’ life, and die each others’ death. Those mortals that die the fiery death become immortal,[390] they become the guardians of the quick and the dead (fr. 123);[391] and those immortals become mortal in their turn. Everything is really the death of something else (fr. 64). The living and the dead are always changing places (fr. 78), like the pieces on a child’s draught-board (fr. 79), and this applies not only to the souls that have become water, but to those that have become fire and are now guardian spirits. The real weariness is continuance in the same state (fr. 82), and the real rest is change (fr. 83). Rest in any other sense is tantamount to dissolution (fr. 84).[392] So they too are born once more. Herakleitos estimated the duration of the cycle which preserves the balance of life and death as thirty years, the shortest time in which a man may become a grandfather (frs. 87-89).[393] Footnote 390: The popular word is used for the sake of its paradoxical effect. Strictly speaking, they are all mortal from one point of view and immortal from another. Footnote 391: We need not hesitate to ascribe to Herakleitos the view that the dead become guardian demons of the living; it appears already in Hesiod, _Works and Days_, 121, and the Orphic communities had popularised it. Rohde, _Psyche_ (pp. 442 sqq.), refused to admit that Herakleitos believed the soul survived after death. Strictly speaking, it is no doubt an inconsistency; but I believe, with Zeller and Diels, that it is one of a kind we may well admit. Many thinkers have spoken of a personal immortality, though there was really no room for it in their systems. It is worthy of note in this connexion that the first argument which Plato uses to establish the doctrine of immortality in the _Phaedo_ is just the Herakleitean parallelism of life and death with sleeping and waking. Footnote 392: These fragments are quoted by Plotinos, Iamblichos, and Noumenios in this very connexion (see R. P. 46 c), and it does not seem to me possible to hold, with Rohde, that they had no grounds for so interpreting them. They knew the context and we do not. Footnote 393: