§61 [388]

And just as it remains questionable whether we can speak of the organism as a historical or even historic being, so too it is questionable whether death and death are the same in the case of man and animal, even if we can identify a physico-chemical and physiological equivalence between the two. From what has been said already it is easy to see that in captivation, as the fundamental structure of life, certain quite determinate possibilities of death, of approaching death, are prefigured. Is the death of the animal a dying or a way of coming to an end? Because captivation belongs to the essence of the animal, the animal cannot die in the sense in which dying is ascribed to human beings but can only come to an end. Consequently the question concerning the essence of the natural physiological death with which the particular living individual intrinsically comes to die—irrespective of external injuries, illnesses, or dangers—represents a central problem. Here too there are many valuable observations to be found in contemporary biology, but they have not yet been seen in their inner connection with the fundamental problem of the essence of animality and of life in general.

This may suffice to remind us of the limited character of our approach to the question. Nevertheless, we can utilize this approach to clarify and to unfold the guiding thesis that the animal is poor in world. Above all we can render our reflections fruitful if we succeed in deciding, on the basis of the essential characterization of the organism we have now acquired, in what relationship this characterization stands to our thesis. Is the thesis that the animal is poor in world merely a proposition that follows from the definition of the essence of the organism, determined as it is by captivation, or on the contrary is this definition grounded in that thesis—grounded not merely to the extent to which we have unfolded it here but in general, so that this thesis could be said to express one of the most originary principles concerning the essence of the organism (of animality)?

Martin Heidegger (GA 29/30) The Fundamental Concepts of Metaphysics