As proof, a brief text from Thomas Aquinas—chosen almost at random, since you can quite easily pile up similar proof-texts. The following is from Summa Theologica I–II, question 3, article 5, body of the text:¹⁰⁰

Si quidem beatitudo in hominis est operatio, oportet quod sit optima opera-tio hominis. Optima autem operatio hominis est, quae est optimae poten-tiae respectu optimi objecti. Optima autem potentia est intellectus, cuius optimum obiectum est bonum divinum, quod quidem non est obiectum practici intellectus, sed speculativi. Unde in tali operatione, scilicet in con-templatione divinorum, maxime consistit beatitudo.

If human happiness is an activity, then it is necessary that it be the best human activity. But the best human activity is the activity of the best human faculty in relation to its best object. {In this passage, Thomas deter-mines what the optima operatio, the best human activity, is. It is the operatio of the optima potentia, the operation of the best and highest human capabil-ity, and it is directed to the optimum obiectum; and optimum est divinum: the best is the divine.}But the best activity is the intellect {that is completely Greek}, whose best object is the divine good. But this divine good is not the object of practical thought, but of speculative thought. {In Scholasticism, speculativus intellec-tus is also used for theoretice,¹⁰¹i.e., it is the Greek θεωρεῖν.}Therefore, it is in such activity {of the theoretical intellect, that is, of pure intuiting in relation to the bonum divinum}—namely, in the pure in-tuition or contemplation of the divine—that there is true and proper hap-piness {i.e., the very highest way of being that human beings as such can have}.

Thomas determines this intelligere—the highest capability human beings as such have—as follows: intelligere nihil aliud est quam praesentia quocumque modo: “[intellect is nothing but] the [123] presence of the knowable to the knowing.” This last understanding of the concept of knowledge comes from Augustine (who in fact is cited in Thomas’s

100.[(1) GA 21, 122.10 incorrectly cites this text as “III” instead of “I–II,” that is, as “Tertia pars” instead of “Prima secundae partis.” Cf. Moser, p. 255.12, and Weiss typescript, p. 61.16. (2) The corpus referred to by Heidegger (rendered here, “body of the text”) is the division of the article in which Thomas presents his own position. (3) Heidegger places his German translation at the end of each complete Latin clause. I gather it, in English after the Latin, and place Heidegger’s running glosses within the English translation.]

101. [Theoretice (gen., theoretices) is a rare Latin noun that translates the Greek (ἐπιστήμη) ϑεωρητική. It refers here to the theoretical or speculative intellect.]