However oblivious the pre-Socratics may have been to the ontological difference (ontologische Differenz) as Heidegger himself thematizes it, they had a profound sense of the Being-process, for they conceived Being (Sein) as φύσις (physis). Whatever it is that spontaneously emerges, or opens-up and unfolds, and, having unfolded, appears in abiding self-manifestation – this is φύσις. It is not simply what we call “nature,” (Nature) which is a being like the rest, sc. only one form of emergence (Aufgehen). Rather it embraces all manner and types of beings: heaven (Himmel) and earth (Erde), gods (Götter) and men (Mensch). By reason of φύσις, beings (Seiende) arise and stand forth as being what they are, sc. they become constant and observable, able-to-be-encountered. Φύσις is emergent-abiding-Power. Whence does it emerge? From concealment (Verborgenheit). Recent philological research finds a relation between the stem φυ- and the φα- of φαίνεσθαι, suggesting that φύσις is an emerging-into-light, a shining-forth, an appearing (Erscheinung). Hence, by reason of φύσις, ἀ-λήθεια (a-letheia) comes-to-pass (GA40:11-12 (auigehenden und verweilenden Waltens), 54, 77 (φυ-, φάινεσθαι), 47 (ἀ-λήθεια)). (RHPT:17)