From charlesreid1

But that which does not exist as an object is, understandably, not given at all, and hence all science has to begin without having a datum of its own; i.e., without having a secure ground under its feet. And what is that which does not exist as an object? For science, everything - even the most tangible, ordinary, and everyday thing, as long as it is only an object of ordinary, everyday life, or an object of the ordinary view of things, but not that of science. A very instructive and interesting example is furnished by the air. It is one of the most essential, proximate, indispensable, and obtrusive external things, and yet it made fools of physicists and philosophers for such a long time before even its elementary properties - weight and expansiveness - became objects for us! Nothing would therefore be more absurd than to characterize the "Beyond, or the realm of the spirits" and similar things or nonsense as not being objects, as unapproachable and mysterious. The realm of the spirits had opened itself to men long before the realm of the air was still closed to them; sooner did they live in the light of another than in that of this world, and sooner did they know the treasures of the heaven than those of the earth.

What is nearest to man is precisely that which is most remote to him - because it has no air of mystery about it, it is no mystery to him; because it is always given to him as an object, it is never an object for him.