Cumulative Record. Chapter 15: Reflections on a Decade of Teaching Machines. Quote 7

In reply to the complaint that he has not produced observable results, the teacher of the mind can lay claim to invisible achievements . . . They may not be able to solve problems, but he has been teaching them simply to think creatively. They may be ignorant of specific facts, but he has been primarily concerned with their general interest in a field. (p. 246)