As noted earlier, there is evidence that much of our thought processes, and hence our ability to create and process "knowledge" have their origins in the senses: what they are, what information they give us, how we process that information, and how we name and categorize that information.
In explaining the basis of mathematics (Initially of arithmetic) Lakoff and Nunez [1] use the concept (q.v) of "conceptual metaphor." They note that, while the word "metaphor" is generally used in the sense of a figure of speech, it is actually the basis of most understanding. These metaphors of understanding are used everywhere humans acquire knowledge, consider knowledge, and communicate knowledge.
And these metaphors are largely constructs of physical sensation, as in acquired by the senses. Much of arithmetical reasoning is based on relative location of things:
Position: this thing is above (below, beside, behind, in front of,...) another thing
Size: this thing is bigger (the same size, smaller, much bigger,...) than that thing
Containing: this thing is inside (outside) of another thing [2]
Blah blah
FOOTNOTES
[1] In their seminal work, Where Mathematics Comes From George Lakoff and Rafael Nunez make a very strong case for the basis of mathematics being a metaphorical extension of the senses. In addition to this revolutionary idea, the authors also explain the why of Euler's Identity: eiπ + 1 = 0, arguably the most symmetrical and beautiful (and rather baffling) mathematical formula. Ever. [Basic Books, First Edition 2001. ISBN 0465037712].
While the book is about the discipline of mathematics as a generalized model, it is no great leap to consider the same origin for any cognitive model and hence the basic founding model of thought itself. Indeed, how would it be any different? Where else would thought originate?
[2] Arguably this is an extension itself of the position metaphor