I. A. Richards: Interpretation in Teaching (1938)

Now, here's a thought:

Thinking is radically metaphoric. … To think of anything is to take it as of a sort … and that 'as' brings in (openly or in disguise) the analogy, the parallel, the metaphoric grapple or ground or grasp or draw by which alone the mind takes hold. (pp. 48–49)

My point is not that language is full of metaphors … It is that thought is itself metaphoric – not merely that it expresses itself in linguistic metaphors. The metaphor that a thought is using need not correspond to the metaphor that its language displays, though it usually does, and the thought will often adopt the verbal metaphor when it is noticed. But equally often we discount and disown the metaphors in our speech, treat them as dead, or kill them as we go. (p. 49)