“By its very nature this entity [= the soul] is suited to come together with all things.”12 In Heidegger’s reading of these texts, Aristotle and Aquinas are not asserting that the soul (read: ex-sistence) is ontically the same as everything in the universe. Rather:

Clearly the soul will be “all things” only with regard to their meaningful presence, and that is because the soul is determined by νοῦς, and νοῦς is determined by ἀληϑεύειν. The soul is the place where things, of and by themselves, can come to appearance. In this way the soul is involved with and participates in the meaningful presence of what is meaningfully present.13

Such participation of the soul in meaningful presence (Anwesen) does not, of course, make Anwesen/Sein into something merely mental. At stake is always the meaningful presence of some thing in space and/or time.

Structurally and in principle we are able to know everything about everything, even though we never will. Such ever-unrealized omniscience comes with our very ex-sistence. (Husserl: “God is the ‘infinitely distant man.’”)14 This open-ended possibility is a “bad infinity,” which in this context denotes the asymptosis of endless progress in knowledge and control.15 Heidegger’s philosophical critique of (as contrasted with his personal opinions about) the modern age of science and technology cannot, on principle, be leveled against our ability to endlessly understand the meanings of things and even to bring them under our control, because this possibility is given with human nature, as Aristotle intimated and as Heidegger accepts in principle. What troubles Heidegger, rather, is the generalized overlooking of one’s mortal thrown-openness in today’s Western, and increasingly global, world. The mystery of human being consists in both the endless comprehensibility of whatever we can meet and the incomprehensibility of why everything is comprehensible. Everything is knowable—except the reason why everything is knowable.16

12. SZ 14.20–21 = 34.37, citing Aquinas, Quaestiones de veritate I, 1, corpus.
13. Heidegger, Übungen im Lesen, 13 February 1952, 45.16–20: “Die Seele wird offensichtlich das Seiende alles nur sein hinsichtlich seines Anwesens, weil nämlich die Seele durch νοῦς bestimmt ist und dieser durch ἀληϑεύειν. Die Seele ist der Ort, wo das Seiende von sich her zum Erscheinen kommen kann. So ist die Seele beteiligt am Anwesen des Anwesenden.” GA 83: 654.8 omits this text.
14. Husserl, Husserliana VI, Die Krisis, 667.29 = 66.18–19: “Gott ist der ‘unendlich ferne Mensch.’”
15. Schlechte Unendlichkeit: see Hegel, Wissenschaft der Logik, Gesammelte Werke, XI, 81.14–15 and 83.11 = 13.14 and 120.21.
16. “[T]he eternal mystery of the world is its comprehensibility”: Albert Einstein, Physics and Reality, 18.