This twofold labor or task, which consists in making the necessary pass into reality in us and in making _out of us_ reality subject to the law of necessity, is urged upon us as a duty by two opposing forces, which are justly styled impulsions or instincts, because they impel us to realize their object. The first of these impulsions, which I shall call the _sensuous instinct_, issues from the physical existence of man, or from sensuous nature; and it is this instinct which tends to enclose him in the limits of time, and to make of him a material being; I do not say to give him matter, for to do that a certain free activity of the personality would be necessary, which, receiving matter, distinguishes it from the Ego, or what is permanent. By matter I only understand in this place the change or reality that fills time. Consequently the instinct requires that there should be change, and that time should contain something. This simply filled state of time is named sensation, and it is only in this state that physical existence manifests itself. As all that is in time is _successive_, it follows by that fact alone that something is: all the remainder is excluded. When one note on an instrument is touched, among all those that it virtually offers, this note alone is real. When man is actually modified, the infinite possibility of all his modifications is limited to this single mode of existence. Thus, then, the exclusive action of sensuous impulsion has for its necessary consequence the narrowest limitation. In this state man is only a unity of magnitude, a complete moment in time; or, to speak more correctly, _he_ is not, for his personality is suppressed as long as sensation holds sway over him and carries time along with it. This instinct extends its domains over the entire sphere of the finite in man, and as form is only revealed in matter, and the absolute by means of its limits, the total manifestation of human nature is connected on a close analysis with the sensuous instinct. But though it is only this instinct that awakens and develops what exists virtually in man, it is nevertheless this very instinct which renders his perfection impossible. It binds down to the world of sense by indestructible ties the spirit that tends higher, and it calls back to the limits of the present, abstraction which had its free development in the sphere of the infinite. No doubt, thought can escape it for a moment, and a firm will victoriously resist its exigencies: but soon compressed nature resumes her rights to give an imperious reality to our existence, to give it contents, substance, knowledge, and an aim for our activity.