It was manifest that at the root of the
whole system of categories there lay the synthetizing unity of
self-consciousness, and it was upon this unity that Fichte fixed as
giving the possibility of a more complete and rigorous deduction of
the pure notions of the understanding. Without the act of the Ego,
whereby it is self-conscious, there could be no knowledge, and this
primitive act or function must be, he saw, the _position_ or
affirmation of itself by the Ego. The first principle then must be
that the Ego posits itself as the Ego, that Ego = Ego, a principle
which is unconditioned both in form and matter, and therefore capable
of standing absolutely first, of being the _prius_ in a system.
Metaphysically regarded this act of self-position yields the
categories of Reality. But, so far as matter is concerned, there
cannot be affirmation without negation, _omnis determinatio est
negatio_. The determination of the Ego presupposes or involves the
Non-Ego. The form of the proposition in which this second act takes to
itself expression, the Ego is not = Not-Ego, is unconditioned, not
derivable from the first. It is the absolute antithesis to the
primitive thesis. The category of Negation is the result of this
second act. From these two propositions, involving absolutely opposed
and mutually destructive elements, there results a third which
reconciles both in a higher synthesis. The notion in this third is
determination or limitation; the Ego and Non-Ego limit, and are
opposed to one another. From these three positions Fichte proceeds to
evolve the categories by a series of thesis, antithesis and synthesis.

In thus seizing upon the unity of self-consciousness as the origin for
systematic development, Fichte has clearly taken a step in advance of,
and yet in strict harmony with, the Kantian doctrine. For, after all
that can be said as to the demonstrated character of formal logic,
Kant's procedure was empirical, and only after the list of categories
had been drawn out, did he bring forward into prominence what gave
them coherence and reality. The peculiar method of Fichte, also, was
nothing but a consistent application of Kant's own Remark on the Table
of the Categories. Fichte's doctrine, however, is open to some of the
objections advanced against Kant. His method is too abstract and
external, and wants the unity of a single principle. The first two of