107. Is the idea of time derived from experience? This question is answered by what we said of the idea of being. It is not a type existing previous to all sensation and to all intellectual act; it is a perception of being and not-being which accompanies all our acts, but is not presented to us separately until reflection eliminates from it all that does not belong to it. This perception is the exercise of an innate activity, which is subjected to the conditions of experience in all that concerns the beginning and the continuation of its acts, but not with respect to its laws which are characteristic of it, and correspond to the pure intellectual order. This activity is unfolded in the presence of causes or occasions which excite it, and its exercise ceases when these conditions are wanting; but while the activity acts, it exercises its functions in accordance with fixed laws which are independent of the objects exciting it. 108. It is therefore clear that the idea of time is not strictly derived from experience, except inasmuch as the mind is excited to develop its activity by experience. Neither is it entirely independent of experience; for without experience we should have no knowledge of change, and consequently the intellect would not perceive the order of being and not-being, in which the essence of time consists. 109. Hence the idea of time is not a form of the sensibility, but of the pure intellectual order; and although it descends to the field of sensible experience, it does so after the manner of other general conceptions. 110. The idea of time is one of the most universal and indeterminate ideas which our mind possesses; for it is the combination of the two most general and most indeterminate ideas, being and not-being. Here is the reason why the idea of time is common to all men, and is presented to us as a form of all our conceptions and of all the objects known. The ideas of being and not-being, entering as primitive elements into all our perceptions, generate the idea of time. We therefore find this idea in the inmost recesses of our soul as a condition from which we cannot withdraw ourselves, and from which we exempt the Infinite Being himself only by an effort of reflection. 111. The transition from the purely intellectual order to the field of experience takes place in the idea of time, in the same manner as in the other intellectual conceptions. I have, therefore, nothing to add to what I have already said on this point when explaining it elsewhere.[31] [31] See Bk. IV., Chapters XIV. and XV. CHAPTER XVI. PURE IDEAL TIME AND EMPYRICAL TIME.