The Critical theory starts originally from the distinction of elements presented in the analysis of experience, viz. the matter of sense, and its universal relations. Taking into account Hume's criticism on this distinction as given in the preceding section, viz. that sensation does not explicitly apprehend more than an individual or more than a mere event, it insists at the same time on the _fact_ that universality and necessity are seen to perform a function equally essential in constituting what is called experience. This element, not being derived from the empirical facts as such, must belong to the spontaneity of thought; in other words, it is _a priori._ The Categories or Notions of the Understanding constitute the _objectivity_ of experiential cognitions. In every case they involve a connective reference, and hence through their means are formed synthetic judgments _a priori,_ that is, primary and underivative connexions of opposites. Even Hume's scepticism does not deny that the characteristics of universality and necessity are found in cognition. And even in Kant this fact remains a presupposition after all; it may be said, to use the ordinary phraseology of the sciences, that Kant did no more than offer another _explanation_ of the fact. 41.] The Critical Philosophy proceeds to test the value of the categories employed in metaphysic, as well as in other sciences and in ordinary conception. This scrutiny however is not directed to the content of these categories, nor does it inquire into the exact relation they bear to one another: but simply considers them as affected by the contrast between subjective and objective. The contrast, as we are to understand it here, bears upon the distinction (see preceding §) of the two elements in experience. The name of objectivity is here given to the element of universality and necessity, _i.e._ to the categories themselves, or what is called the _a priori_ constituent. The Critical Philosophy however widened the contrast in such away, that the subjectivity comes to embrace the _ensemble_ of experience, including both of the aforesaid elements; and nothing remains on the other side but the 'thing-in-itself.' The special forms of the _a priori_ element, in other words, of thought, which in spite of its objectivity is looked upon as a purely subjective act, present themselves as follows in a systematic order which, it may be remarked, is solely based upon psychological and historical grounds. * * * * *