Lewis's last version of the argument from reason

Lewis's Last Version of the Argument from Reason
The Discarded Image was published posthumously.

No Model yet devised has made a satisfactory unity between our actual experience of sensation or thought or emotion and any available account of the corporeal processes which they are held to involve. We experience, say, a chain of reasoning; thoughts, which are ‘about’ or ‘refer to’ something other than themselves, are linked together by the logical relation of grounds and consequents. Physiology resolves this into a sequence of cerebral events. But physical events, as such, cannot in any intelligible sense be said to be ‘about’ or to ‘refer to’ anything. And they must be linked to one another not as grounds and consequents but as causes and effects—a relation so irrelevant to the logical linkage that it is just as perfectly illustrated by the sequence of a maniac’s thoughts as by the sequence of a rational man’s.” C. S. Lewis, The Discarded Image: An Introduction to Medieval and Renaissance Literature (Cambridge: Cambridge Univ. Press, 1964), 165-6.