becomes visible by means of matter, the thing in itself, the will. Gravity is yet the lowest of all grades of the objectification of the will; therefore it appears in all matter without exception, thus is inseparable from matter in general. Yet, just because it is a manifestation of the will, it belongs to knowledge _a posteriori_, not to knowledge _a priori_. Therefore we can always picture to ourselves matter without weight, but not without extension, repulsive force, and stability, for then it would be without impenetrability, and consequently would not occupy space, _i.e._, it would be without _the power of acting_; but the nature of matter as such just consists in _acting_, _i.e._, in causality in general; and causality depends upon the _a priori_ form of our understanding, and therefore cannot be thought away. Matter is accordingly the _will_ itself, but no longer in itself, but so far as it is _perceived_, _i.e._, assumes the form of the objective idea. Thus what objectively is matter is subjectively will. Exactly corresponding to this, as was proved above, our body is just the visibility, objectivity of our will, and so also every body is the objectivity of the will at some one of its grades. Whenever the will exhibits itself to objective knowledge it enters into the forms of perception of the intellect, time, space, and causality. But on account of this it exists at once as a _material_ object. We can present to our minds form without matter, but not the reverse; because matter deprived of form would be the will itself, and the will only becomes objective by entering the forms of perception of our intellect, and therefore only by means of the assumption of form. Space is the form of perception of matter because the latter is the substance (Stoff) of mere form, but matter can _appear_ only in form.