Martin Heidegger,

Human existence can relate to beings only if it holds itself out into the nothing. Going beyond beings occurs in the essence of Dasein. But this going beyond is metaphysics itself. This implies that metaphysics belongs to the "nature of man." It is neither a division of academic philosophy nor a field of arbitrary notions. Metaphysics is the basic occurrence of Dasein. It is Dasein itself. Because the truth of metaphysics dwells in this groundless ground it stands in closest proximity to the constantly lurking possibility of deepest error. For this reason no amount of scientific rigor attains to the seriousness of metaphysics. Philosophy can never be measured by the standard of the idea of science.If the question of the nothing unfolded here has actually questioned us, then we have not simply brought metaphysics before us in an extrinsic manner. Nor have we merely been "transposed" to it. We cannot be transposed there at all, because insofar as we exist we are always there already. "For by nature, my friend, man's mind dwells in philosophy" (Plato, Phaedrus, 279a). So long as man exists, philosophizing of some sort occurs. Philosophy__hat we call philosophy__s metaphysics getting under way, in which philosophy comes to itself and to its explicit tasks. Philosophy gets under way only by a peculiar insertion of our own existence into the fundamental possibilities of Dasein as a whole. For this insertion it is of decisive importance, first, that we allow space for beings as a whole; second, that we release ourselves into the nothing, which is to say, that we liberate ourselves from those idols everyone has and to which he is wont to go cringing; and finally, that we let the sweep of our suspense take its full course, so that it swings back into the basic question of metaphysics which the nothing itself compels: 'Why are there beings at all, and why not rather nothing?"__rom_What is Metaphysics?_

Metaphysics thinks about beings as beings. Wherever the question is asked what beings are, beings as such are in sight. Metaphysical representation owes this sight to the light of Being. The light itself, i.e., that which such thinking experiences as light, does not come within the range of metaphysical thinking; for metaphysics always represents beings only as beings. Within this perspective, metaphysical thinking does, of course, inquire into the being which is the source and originator of this light. But the light itself is considered sufficiently illuminated as soon as we recognize that we look through it whenever we look at beings.In whatever manner beings are interpreted__hether as spirit, after the fashion of spiritualism; or as becoming and life, or idea, will, substance, subject, or *energeia*; or as the eternal recurrence of the same events__very time, beings as beings appear in the light of Being. Wherever metaphysics represents beings, Being has entered into the light. Being has arrived in a state of unconcealedness (aletheia). But whether and how Being itself involves such unconcealedness, whether and how it manifests itself in, and as, metaphysics, remains obscure. Being in its revelatory essence, i.e., in its truth, is not recalled. Nevertheless, when metaphysics gives answers to its question concerning beings as such, metaphysics speaks out of the unnoticed revealedness of Being. The truth of Being may thus be called the ground in which metaphysics, as the root of the tree of philosophy, is kept and from which it is nourished.Because metaphysics inquires about beings as beings, it remains concerned with beings and does not devote itself to Being as Being. As the root of the tree, it sends all nourishment and all strength into the trunk and its branches. The root branches out in the soil to enable the tree to grow out of the ground and thus to leave it. The tree of philosophy grows out of the soil in which metaphysics is rooted. The ground is the element in which the root of the tree lives, but the growth of the tree is never able to absorb this soil in such a way that it disappears in the tree as part of the tree. Instead, the roots, down to the subtlest tendrils, lose themselves in the soil. The ground is ground for the roots, and in the ground the roots forget themselves for the sake of the tree...Metaphysics, insofar as it always represents only beings as beings, does not recall Being itself. Philosophy does not concentrate on its ground. It always leaves its ground__eaves it by means of metaphysics. And yet, it never escapes its ground...Insofar as a thinker sets out to experience the ground of metaphysics, insofar as the attempts to recall the truth of Being itself instead of merely representing beings as beings, his thinking has in a sense left metaphysics. From the point of view of metaphysics, such thinking goes back into the ground of metaphysics."__rom_The Way Back to the Ground of Metaphysics_

Philosophy is metaphysics. Metaphysics thinks beings as a whole__he world, man, God__ith respect to Being, with respect to the belonging together of beings in Being. Metaphysics thinks beings as being in the manner of representational thinking which gives reasons. For since the beginning of philosophy and with that beginning, the Being of beings has showed itself as the ground (arche, aition, principle). The ground is that from which beings as such are what they are in their becoming, perishing, and persisting as something that can be known, handled, and worked upon. As the ground, Being brings beings to their actual presencing. The ground shows itself as presence. The present of presence consists in the fact that it brings what is present each in its own way to presence. In accordance with the actual kind of presence, the ground has the character of grounding as the ontic causation of the real, as the transcendental making possible of the objectivity of objects, as the dialectical mediation of the movement of the absolute Spirit and of the historical process of production, as the will to power positing values."__rom_The End of Philosophy and the Task of Thinking_

Human existence can relate to beings only if it holds itself out into the nothing. Going beyond beings occurs in the essence of Dasein. But this going beyond is metaphysics itself. This implies that metaphysics belongs to the "nature of man." It is neither a division of academic philosophy nor a field of arbitrary notions. Metaphysics is the basic occurrence of Dasein. It is Dasein itself. Because the truth of metaphysics dwells in this groundless ground it stands in closest proximity to the constantly lurking possibility of deepest error. For this reason no amount of scientific rigor attains to the seriousness of metaphysics. Philosophy can never be measured by the standard of the idea of science.If the question of the nothing unfolded here has actually questioned us, then we have not simply brought metaphysics before us in an extrinsic manner. Nor have we merely been "transposed" to it. We cannot be transposed there at all, because insofar as we exist we are always there already. "For by nature, my friend, man's mind dwells in philosophy" (Plato, Phaedrus, 279a). So long as man exists, philosophizing of some sort occurs. Philosophy__hat we call philosophy__s metaphysics getting under way, in which philosophy comes to itself and to its explicit tasks. Philosophy gets under way only by a peculiar insertion of our own existence into the fundamental possibilities of Dasein as a whole. For this insertion it is of decisive importance, first, that we allow space for beings as a whole; second, that we release ourselves into the nothing, which is to say, that we liberate ourselves from those idols everyone has and to which he is wont to go cringing; and finally, that we let the sweep of our suspense take its full course, so that it swings back into the basic question of metaphysics which the nothing itself compels: 'Why are there beings at all, and why not rather nothing?'"__rom_What is Metaphysics?_