The actions expressed in the three principles are never found pure in experience, nor do they represent isolated acts of the ego.  Intelligence can think nothing without thinking itself therewith; it is equally impossible for it to think “I am” without at the same time thinking something else which is not itself; subject and object are inseparable.  It is rather true that the acts of position described are one single, all-inclusive act, which forms only the first member in a connected system of pre-conscious actions, through which consciousness is produced, and the complete investigation of whose members constitutes the further business of the Science of Knowledge as a theory of the nature of reason.  In this the Science of Knowledge employs a method which, by its rhythm of analysis and synthesis, development and reconciliation of opposites, became the model of Hegel’s dialectic method.  The synthesis described in the third principle, although it balances thesis and antithesis and unites them in itself, still contains contrary elements, in order to whose combination a new synthesis must be sought.  In this, in turn, the analytic discovery and the synthetic adjustment of a contrariety is repeated, etc., etc.  The original synthesis, moreover, prescribes a division of the inquiry into two parts, one theoretical and the other practical.  For it contains the following principles:  The ego posits itself as limited by the non-ego—­it functions cognitively; and:  The ego posits itself as determining the non-ego—­it functions volitionally and actively.

%(c) The Theoretical Ego.%—­In positing itself as determined by the non-ego, the ego is at once passive (affected by something other than itself) and active (it posits its own limitation).  This is possible only as it posits reality in itself only in part, and transfers to the non-ego so much as it does not posit in itself.  Passivity is diminished activity, negation of the totality of reality.  From reflection on this relation between ego and non-ego spring the categories of reciprocal determination, of causality (the non-ego as the cause of the passion of the ego), and substantiality (this passion merely the self-limitation of the ego).  The conflict between the causality of the non-ego (by which the ego is affected) and the substantiality of the ego (in which and the activity of which all reality is contained) is resolved only by the assumption of two activities (or, rather, of two opposite directions of one activity) in the ego, one of which (centrifugal, expansive) strives infinitely outward while the other (centripetal or contractile) sets a bound to the former, and drives the ego back into itself, whereupon another excursus follows, and a new limitation and return, etc.  With every repetition of this double act of production and reflection a special class of representations arises.  Through the first limitation of the in itself unlimited activity “sensation” arises (as a product of the “productive imagination").