Translated by Pete Ferreira
Now, precisely because of this absolutizing, which leads him to conceive and to formulate in a clear and determined manner the central problem of his own philosophizing, Heidegger adopts in his confrontations with Aristotelian thought on the problem of the 'subject', a critical attitude that coincides with a distancing, necessary toward the end of his confrontation on the question of truth, and which then confirms it.
In fact, the absolutizing and radicalizing in an ontological sense of the practical determination of human life leads only to individualization and the thematic connotation of the different existentials, but comes closer to grasping the unitary ontological structure of being-there, which is the basis of being, i.e. on grasping the structure that is represented, as we know, in care in its temporal character, that is, by its originary temporality (so designated to distinguish it from temporality understood naturalistically). In Aristotelian thought, on the other hand, from which comes the eminently practical sense of awareness by which human life refers to itself, from the relationship of being-there to being itself, the problem of the unitary way of being of man would not be asked with sufficient radicalism. For Heidegger, then, Aristotle would have provided a genial 'phenomenology' of the fundamental determinations of human life (θεωρία, ποίησις, πρᾶξις, and all the others we have mentioned and that Heidegger appropriates), without yet however explicitly asking the question of their fundamental unity.
And the reason for this omission lies for Heidegger in the fundamental assumption that underlies Aristotelian thought and which had already influenced the interpretation that it gave the phenomenon of truth, namely the assumption of a certain understanding of time and a certain understanding of being, in which the connection of being and time is not captured in all its implications. And precisely because Aristotle would remain tied to a naturalistic conception of time, he would not persevere on to grasp originary temporality as the basic unity of the determinations of human life. Let us see, then, how Heidegger faces the problem of temporality.
To understand Heidegger's approach to the problem of temporality – in particular to correctly understand Heidegger's conception of originary temporality as a structure of human life itself in opposition to the naturalistic conception of time – it is important to note that already in the first Freiburg courses Heidegger had examined and pointed out the differences between the time of the Greeks' 'chronological' understanding and the 'kairological' experience of time typical of early Christianity. He had illustrated especially how in the latter, in relation to the expectation of the return of Christ and in connection with the fact that such a coming calls for being prepared (since, as St. Paul recalled, he will come "like a thief in the night"), it leads to a real breakthrough in understanding the temporal character of human existence.51
51 See O. Pöggeler, Der Denkweg Martin Heideggers, pp. 36-45; Sheehan, Heidegger e il suo corso sulla 'Fenomenologia della religione' (1920-21), op. cit., especially pp. 443 ff.