But, while "the Speculative Reason" is held to be incompetent to prove the existence of God, "the Practical Reason" is appealed to; and in the conscious liberty of the soul, and its sense of incumbent moral duty,--"the Categorical Imperative,"-- Kant finds materials for reconstructing the basis and fabric of a true Theology, not scientifically perfect, but practically sufficient for all the purposes of life.
It was scarcely possible that Philosophy could find a permanent resting-place in such a theory as this; for, while it recognized both the "object" and the "subject" as equally indispensable, the one for the _matter_, the other for the _form_, of human knowledge, it did not hold the balance even between the two.

It assigned so much to the "subject," and so little to the "object," and made so large a part of our knowledge merely formal and subjective, that it could neither be regarded as a self-consistent system of Skepticism, nor yet as a satisfactory basis for Scientific Belief.

It was almost inevitable that speculative minds, starting from this point, should diverge into one or other of _three_ courses; either following the line of the "subject" exclusively, and treating the "object" as a superfluous incumbrance, so as to reach, as Schulz and Maimon did, a pure Subjective Idealism, akin to utter Skepticism; or following the line of the "object," and giving it greater prominence than it had in the system of Kant, so as to lay the foundation, as Jacobi and Herbart did, of a system of Objective Certitude; or keeping _both_ in view, and attempting, as Fichte, Schelling, and Hegel did, to blend the two into one, so as to reduce them to systematic unity.[135] In Kant's system a _dualism_ was admitted, a real distinction between the "subject" and "object" of thought; but he had ascribed so much to the subject, and so little to the object, that Fichte conceived the idea of dispensing with the latter altogether, and constructing his whole philosophy on a purely subjective basis.

Since Kant had taught that all objects are conceived of either according to the forms of our sensational faculty, or the categories of our understanding, or the ideas of pure reason, it seemed to be unnecessary to suppose the existence of any object distinct from the mind itself.

For if it be the mind which furnishes the form of Space, and gives us the idea of Substance, of Cause, of Being, the mind alone might suffice to account for the whole sum of human knowledge.