The burden and blessing of mortality.

Since time immemorial, mortals have bewailed their mortality, have longed to escape it, groped for some hope of eternal life. I speak, of course, of human mortals. Men alone of all creatures know that they must die, men alone mourn their dead, bury they dead, remeber their dead. So much is mortality taken to mark the human condition, that the attribute "mortal" has tended to be monompolized for man: in Homeric and later Greek usage, for example, "mortals" is almost a synonym for "men," contrasting them to the envied, ageless immortality of the gods. Memento mori rings through the ages as a persistent philosophical and religious admonition in aid of a truly human life. As Psalm 90 puts it, "Teach us to number our days, that we may get a heart of wisdom. " Over this incurably anthropocentric emphasis, not much thought was spent on the obvious truth that we share the lot of mortality with our fellow creatures, that all life is mortal, indeed that death is coextensive with life. Reflection shows that this must be so; that you cannot have the one without the other. Let this be our first theme: mortality as an essential attribute of life as such--only later to focus on specifically human aspects of it. Two meanings merge in the term mortal: that the creature so called can die, is exposed to the constant possibility of death; and that, eventually, it must die, is destined for the ultimate necessity of death. In the continual possibility I place the burden, in the ultimate necessity I place the blessing of mortality. The second of these propositions may sound strange. Let me argue both. I begin with mortality as the ever-present potential of death for everything alive, concurrent with the life process itself. This "potential" means more than the truism of being destructible, which holds for every composite material structure, dead or alive. With sufficient force, even the diamond can be crushed, and everything alive can be killed by any number of outside causes, prominent among them other life. However, the inmost relation of life to possible death goes deeper than that: it resides in the organic constitution as such, in its very mode of being. I have to spell out this mode to lay bare the roots of mortality in life itself. To this end I now beg you to keep me company on a stretch of ontological inquiry. By this, we philosophers mean an inquiry into the manner of being characteristic of entities of one kind or another--in our case, of the kind called "organism," as this is the sole physical form in which, to our knowledge, life exists. What is the way of being of an organism? Our opening observation is that organisms are entities whose being is their own doing. That is to say that they exist only in virtue of what they do. And this in the radical sense that the being they earn from this doing is not a possesion they then own in spearation from the activity by which it was generated, but is the continuation of that very activity itself, made possible by what it has just performed. Thus to say that the being of organisms is their own doing is also to say that doing what they do is their being itself; being for them consists in doing what they have to do in order to go on to be. It follows directly that to cease doing it means ceasing to be; and since the requisite doing depends not on themselves alone, but also on the compliance of an environment that can either be granted or denied, the peril of cessation is with the organism from the beginning. Here we have the basic link of life with death, the ground of mortality in its very constitution. What we have couched so far in the abstract terms of being and doing, the language of ontology, can now be called by its familiar name: metabolism. This concretely is the 'doing' referred to in our opening remark about entities whose being is their own doing, and metabolism can well serve as the defining property of life: all living things have it, no nonliving thing has it. …