vel alio aliquo modo sensus afficiens: sed tantum in eo quod sit res extensa in longum, tatum et profundum ."xx
If we subject Descartes' Interpretation of the experience of hardness and resistance to a critical analysis, it will be plain how unable he is to let what shows itself in sensation present itself in its own kind of Being, 1 or even to determine its character (Cf. Section 19).
Hardness gets taken as resistance. But neither hardness nor resistance is understood in a phenomenal sense, as something experienced in itself whose nature can be determined in such an experience. For Descartes, resistance amounts to no more than not yielding place—that is, not undergoing any change of location. So if a Thing resists, this means that it stays in a definite location relatively to some other Thing which is changing its location, or that it is changing its own location with a velocity which permits the other Thing to 'catch up' with it. But when the experience of hardness is Interpreted this way, the kind of Being which belongs to sensory perception is obliterated, and so is any possibility that the entities encountered in such perception should be grasped in their Being. Descartes takes the kind of Being which belongs to the perception of something, and translates it into the only kind he knows: the perception of something becomes a definite way of Being-present-at-hand-side-by-side of two res extensae which are present-at-hand; the way in which their movements are related is itself a mode of that extensio by which the presence-at-hand of the corporeal Thing is primarily characterized. Of course no behaviour in which one feels one's way by touch [ eines tastenden Verhaltens] can be 'completed' unless what can thus be felt [des Betastbaren] has 'closeness' of a very special kind. But this does not mean that touching [Berührung] and the hardness which makes itself known in touching consist ontologically in different velocities of two corporeal Things. Hardness and resistance do not show themselves at all unless an entity has the kind of Being which Dasein—or at least something living—possesses.
Thus Descartes' discussion of possible kinds of access to entities withinthe- world is dominated by an idea of Being which has been gathered from a definite realm of these entities themselves.
The idea of Being as permanent presence-at-hand not only gives Descartes a motive for identifying entities within-the-world with the world in general, and for providing so extreme a definition of their Being; it also keeps him from bringing Dasein's ways of behaving into view in a manner which is ontologically appropriate. But thus the road is completely
1 '... das in der Sinnlichkeit sich Zeigende in seiner eigenen Seinsart sich vorgeben zu lassen ...'