[0]I say Reason, and not cognition, because for Kant cognition is empirical, and the purpose of the Critique of Pure Reason is to find the conditions of possibility for empirical reality to appear to us, so the total system that, in its reflection, can make those conditions appear to us (that is, the Critique itself), cannot, although it appears to the senses, actually itself be from within them--it must be purely intelligible. If you're curious how Kant solves this dilemma, well, so was everyone else, and the whole of the German, and then later anglo-american and French philosophical traditions have been remarkably pre-occupied with this question.
In science, we talk of bridging fields, or filling in gaps, as if science is a landscape to be explored. Math is organised into topics that are linked together by “deep connections”.