metaphysics itself demands and seeks anew time and again) with the sciences, themselves the offspring of metaphysics, preparatory thinking must also move now and then in the area of the sciences because in many different shapes they are claiming still to predetermine the fundamental form of knowledge and the knowable, either knowingly or through the nature of their validity and effectiveness. The more plainly the sciences are carried along by their predetermined technological essence and its characteristic forn1, the more definitely the question is resolved about the epistemological possibility claimed in technology, about the nature, limits, and rights of this possibility for knowledge.

To think preparatorily and to fulfill such thinking involves an education in thinking in the midst of the sciences. For this, the difficult thing is to find an appropriate form so that this education in thinking is not liable to be confused with research and erudition. This goal is in danger above all when thinking must, simultaneously and perpetually, first of all find its own place to stay. To think in the midst of the sciences means: to go past them without despising them.

We do not know what possibilities the destiny of Western history still has in store for our people and the West. Nor is the external organization and arrangement of these possibilities what is necessary in the first instance. What is important is only that learners in thinking are fellow learners — fellow learners who in their own way stay on the path and are present at the right moment.

The following commentary, in its intention and consequence, keeps to the area of the one experience out of which Being and Time is thought. This thinking has been concerned constantly with one occurrence: that in the history of Western thinking, right from the beginning, beings have been thought in regard to being, but the truth of being has remained un-thought. Indeed, not only has the truth of being been denied to thinking as a possible experience, but Western thinking itself (precisely in the form of metaphysics) has specifically, though unknowingly, masked the occurrence of this denial.a

Preparatory thinking therefore necessarily keeps to the realm of historical reflection. For this thinking, history is not the sequence of historical periods but a unique proximity of what is the same, which concerns thinking in the incalculable ways of destiny and with variable degrees of immediacy.

a First edition, 1950: denial and withholding.