Objective and subjective are convenient expressions in current use, the employment of which may easily lead to confusion. Up to this point, the discussion has shown three meanings of objectivity. First, it means what has external existence, in distinction from which the subjective is what is only supposed, dreamed, &c. Secondly, it has the meaning, attached to it by Kant, of the universal and necessary, as distinguished from the particular, subjective and occasional element which belongs to our sensations. Thirdly, as has been just explained, it means the thought-apprehended essence of the existing thing, in contradistinction from what is merely _our_ thought, and what consequently is still separated from the thing itself, as it exists in independent essence. 42.] (a) The Theoretical Faculty.--Cognition _quâ_ cognition. The specific ground of the categories is declared by the Critical system to lie in the primary identity of the 'I' in thought,--what Kant calls the 'transcendental unity of self-consciousness.' The impressions from feeling and perception are, if we look to their contents, a multiplicity or miscellany of elements: and the multiplicity is equally conspicuous in their form. For sense is marked by a mutual exclusion of members; and that under two aspects, namely space and time, which, being the forms, that is to say, the universal type of perception, are themselves _a priori._ This congeries, afforded by sensation and perception, must however be reduced to an identity or primary synthesis. To accomplish this the 'I' brings it in relation to itself and unites it there in _one_ consciousness which Kant calls 'pure apperception.' The specific modes in which the Ego refers to itself the multiplicity of sense are the pure concepts of the understanding, the Categories.