117. This internal activity, by which, at our will or caprice, we produce an indefinite number of representations, with an indefinite variety of forms, is an important phenomenon and one worthy of attention. It shows us that the productive activity is not limited to the purely intellectual order, since we detect it in the sensible order, not in any way whatever, but as unrolled on an infinite scale. Suppose a right line to be produced to infinity, besides it and in the same plane, we may infinite other lines; the variety of angles in which we may consider the position of the different lines will extend to the infinite; so that with right lines alone, the productive activity in the order of sensibility will know no limit. If we substitute curves for right lines, their combinations in form, in nature, in their respective positions and relations with determinate axes, will likewise be infinite: so that without quitting the sensible order, we discover within ourselves a force productive of infinite representations, and one needing no elements besides terminable or figurable extension. 118. The representative sensible faculty develops itself sometimes by the presence of an object; at other times, spontaneously, without any dependence on the will; and finally, at other times, in consequence of a free act. This is not the place to examine in what way the phenomenon of representation is connected with the affections of the corporeal organs; at present, we propose only to designate and explain facts in the ideological sphere, absolutely abstracting their physiological aspect. Among the sensible representations just classified, which we may call _passive_, _spontaneous_, and _free_, there are differences worthy of observation. 119. Passive representation is given to the soul, independently of its activity. If we be placed in presence of an object, with our eyes open, it will be impossible not to see it, or even not to see it in a certain manner, if we do not change the direction of our eyesight or other condition of vision. For this reason, the soul seems, in the exercise of its senses, to be purely passive, since its representations necessarily depend on the conditions to which its corporeal organs in their relation to objects, are subject. 120. Spontaneous representation, or the faculty productive of sensible representations, seems also, since it operates independently of external objects and of the will, to be more or less passive, and its exercise to depend upon organic affections. And the fact that these sensations are wont to exist without any order, or at most, if they are recollections of old sensations, with that only which they had at another time, appears to indicate it. It is also worthy of note that these representations are sometimes offered to us, in spite of all the efforts of the will to dissipate and forget them: some are so tenacious as for a long time to triumph over all the resistance of freewill.