Empirical knowledge, he observes with Plato, is founded on ideal conception, yet it never comprises the whole truth of the ideal conception. The conditioned and finite tends toward the infinite which it never reaches. For experience forbids true knowledge, and true knowledge is itself relative, always aiming at greater truth. Experience, says Cusanus, is really hypothesis, conjecture. In this conception of Conjecture he finds the link between Creator and Creation, Idea and Manifestation .
Conjecture is a positive assertion in place of truth, having some part in truth.
Single truth can only be manifested to us in difference, but there is no difference which does not in some sort attain to and have part in this unity. From these thoughts and not on physical but on metaphysical grounds, the De docta ignorantia and the De coniecturis develop the idea both of the motion of the earth and of the relativity of all motion. The infinity of the universe is envisaged as bound up with the identity of contraries. The same thought recurs repeatedly in his works. In the De pace fidei the conception is applied to differences of belief.