The pupil who is never required to do what he cannot do, never does what he can do.

The remark argues that genuine education requires stretch and difficulty. If a student is only ever assigned tasks already within easy reach, they will not develop latent capacities; challenge is what elicits effort, ingenuity, and growth. The paradoxical phrasing (“never required to do what he cannot do…”) suggests that being asked to attempt the currently impossible is precisely what expands the possible. It also implies a critique of overly protective or low-expectation pedagogy: without demanding goals, learners may settle into minimal performance and never discover what they are capable of achieving.