Miracles 3.19 Lewis identifies "being known" as a mode of causation. It is known through the thing known and not from another source. If explicable from another source, Lewis uses the example of tinnitus to that extent it is not knowledge. Failing an explanation of this sort Lewis claims would be a "theory that there is no reasoning."
Miracles 3.30 "To call the act of knowing -- the act, not of remembering that something was so in the past, but of 'seeing' that it must be so always and in any possible world -- to call this act 'supernatural' ... [is to mean] only that it 'won't fit in'; ..."
Miracles 4.1 "If our argument has been sound, acts of reasoning are not interlocked with the total interlocking system of Nature as all its other items are interlocked with one another." (contrasts understanding with the thing understood)