‘Logic’ is the shortened expression for ἐπιστήμη λογική, and now means: having an understanding of what pertains to λόγος. And what does λόγος now mean? We let the question stand once more and linger first with the historical ‘fact’ that the name and matter of ἐπιστήμη λογική arises in connection with two other names and matters—ἐπιστήμη φυσική and ἐπιστήμη ἠθική—and in a manner that becomes historical.
ἐπιστήμη φυσική is the understanding of what belongs to φύσις or, more precisely, to the φύσει ὄντα . These are those particular beings that, emerging and submerging on their own accord, safeguard arising and vanishing: heaven and earth, the stars, the ocean, the mountains, rocks and waters, plants and animals.  If we thus understand the emerging and the emerged as what presences and appears in the broadest sense, then even humans and gods belong to φύσει ὄντα, insofar as they appear and presence, decay and disappear, peer into the unconcealed and withdraw themselves. ἐπιστήμη φυσική—that is, physics thus understood—is the knowledge of beings as a whole, in all of their guises and stages, in terms of their first and simplest connections. This ‘physics’ is not only substantially wider in scope than what we think of as ‘physics’ today (i.e., the mathematical, experimental knowledge pertaining to the laws of motion of material points of mass in space and time). ἐπιστήμη φυσική also thinks in a completely different way than the modern science of physics—indeed, in a completely different way than all science. ἐπιστήμη φυσική thinks beings as a whole, and thereby also beings in general, with an eye toward what is common to every being insofar as it is, can be, must be, or is none of these. What is common, proper, and ownmost to all beings is ‘being.’ ‘Being’—the emptiest word which, it would appear, makes us initially not think much at all. Being—the word from out of which we nevertheless think and experience everything, and the word through which we are . When will we finally have the ‘courage,’ for once, to think genuinely and tenaciously what would come to be if we (i.e., humans) could not think and say ‘being’ and ‘to be’? The ἐπιστήμη φυσική of the ancient Greeks is a way and an attempt to understand beings as a whole with an eye toward being, an attempt to place themselves before beings and stand before them so that these beings may show themselves in their being. The entirety of Occidental thinking has not moved beyond this attempt—at most, perhaps, it has deviated from it.
The third term, ἐπιστήμη ἠθική, designates the understanding of what belongs to the ἦθος . The word ἦθος originally means dwelling, sojourn. Here, in the term ἐπιστήμη ἠθική, τὸ ἦθος is meant in a simple way. So understood, it means  the sojourn of the human, the residing, the ‘dwelling’ of the human in the midst of beings as a whole. The essential feature of ἦθος, of this sojourning, is the way in
156 Logic: Heraclitus’s Doctrine of the Logos