Do not confound thought with thinking. Thought is the Object that you think. Thinking, as contradistinguished from feeling and from the effort of attention, is the operation of the mind by which you strive to make out the Truth. You expect to extract it from the object before your mind, the Thought.
‘Thinking’ is a fabled ‘operation of the mind’ by which an imaginary object is brought before one’s gaze. If that object is a Sign upon which an argument may turn, we call it a Thought. All that we know of the ‘Thinking’ is that we afterwards remember that our attention was actively on the stretch, and that we seemed to be creating Objects or transformations of Objects while noting their analogy to something supposed to be real. We choose to call ‘an operation of the mind’; and we are, of course, quite justified in doing so, provided it be well understood that its being so consists merely in our so regarding it, just as Alexander, Hannibal, Caesar, and Napoleon constitute a single quaternion, or plural of four, as long as we put them together in thought. The ‘operation of the mind’ is an ens rationis. That is my insufficient excuse for speaking of it as ‘fabled’.