ON THE ESSENCE AND CONCEPT OF Φύσις
is a presencing, namely, that kind in which the absencing (but not the absent thing) is present. Στέρεσις is εἶδος, but εἶδος πως, an appearance and presencing of sorts. Today we are all too inclined to reduce something like this presencing-by-absencing to a facile dialectical play of concepts rather than hold on to what is astonishing about it. For in στέρεσις is hidden the essence of φύσις. To see this we must first answer the next question.
Re (2) How is στέρεσις related to μορφή? The self-placing into the appearance is κίνησις, a change from something to something, a change that in itself is the "breaking out" of something. When wine becomes sour and turns to vinegar, it does not become nothing. When we say, "It has turned to vinegar," we mean to indicate that it came to "nothing," i.e., to what we had not expected. In the "vinegar" lies the nonappearance, the absencing, of the wine. Μορφή as γένεσις is ὁδός, the being-on-the-way of a "not yet" to a "no more." The self-placing into the appearance always lets something be present in such a way that in the presencing an absencing simultaneously becomes present. 'While the blossom "buds forth" (φύει), the leaves that prepared for the blossom now fall off. The fruit comes to light, while the blossom disappears. The self-placing into the appearance, the μορφή, has a στέρεσις-character, and this now means: μορφή is διχῶς, intrinsically twofold, the presencing of an absencing. Consequently the third question already has its answer.
Re (3) In what sense is the essence of φύσις twofold? As φύσεως ὁδός εἰς φύσιν, φύσις is a kind of ἐνέργεια, a kind of οὐσία. Specifically it is production of itself, from out of itself, unto itself. Nonetheless, in essentially "being-on-the-way," each being that is pro-duced or put forth (excluding artifacts) is also put away, as the blossom is put away by the fruit. But in this putting away, the self-placing into the appearance — φύσις — does not cease to be. On the contrary, the plant in the form of fruit goes back into its seed, which, according to its essence, is nothing else but a going-forth into the appearance, ὁδός φύσεως εἰς φύσιν. With its very coming-to-life every living thing already begins to die, and conversely, dying is but a  kind of living, because only a living being has the ability to die. Indeed, dying can be the highest "act" of living. Φύσις is the self-productive putting-away of itself, and therefore it possesses the unique quality of delivering over to itself that which through it is first transformed from something orderable (e.g., water, light, air) into something appropriate for it alone (for example, into nutriment and so into sap or bones). One can take this "appropriate" for itself as the orderable and consider this orderable as material, and therefore take φύσις as mere "change of material." One can further reduce the material to what is most constantly present in it, and take this as the stable,