he must give form to matter, and in order not to be a mere form, he must give reality to the virtuality that he bears in him.  He gives matter to form by creating time, and by opposing the immutable to change, the diversity of the world to the eternal unity of the Ego.  He gives a form to matter by again suppressing time, by maintaining permanence in change, and by placing the diversity of the world under the unity of the Ego.

Now from this source issue for man two opposite exigencies, the two fundamental laws of sensuous-rational nature.  The first has for its object absolute reality; it must make a world of what is only form, manifest all that in it is only a force.  The second law has for its object absolute formality; it must destroy in him all that is only world, and carry out harmony in all changes.  In other terms, he must manifest all that is internal, and give form to all that is external.  Considered in its most lofty accomplishment, this twofold labour brings us back to the idea of humanity which was my starting-point.

LETTER XII.

This twofold labour 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 realise their object.  The first of these impulsions, which I shall call the sensuous instinct, issues from the physical existence of roan, 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.