For example, he speaks of space and time, cause and effect, substance and qualities, matter and mind, reality and unreality.

He certainly is in a position to add to our knowledge of the things covered by these terms.

But we should never overlook the fact that the new knowledge which he gives us is a knowledge of the same kind as that which we had before.

He measures for us spaces and times; he does not tell us what space and time are.

He points out the causes of a multitude of occurrences; he does not tell us what we mean whenever we use the word "cause." He informs us what we should accept as real and what we should repudiate as unreal; he does not try to show us what it is to be real and what it is to be unreal.
In other words, the man of science _extends_ our knowledge and makes it more accurate; he does not _analyze_ certain fundamental conceptions, which we all use, but of which we can usually give a very poor account.
On the other hand, it is the task of _reflective thought_, not in the first instance, to extend the limits of our knowledge of the world of matter and of minds, but rather _to make us more clearly conscious of what that knowledge really is_.