The remark separates the content of schooling from its lasting effect. Dates, formulas and vocabulary lists are largely forgotten once examinations are over, yet something is left behind: habits of thought, curiosity, the capacity to reason and the ability to approach an unfamiliar problem. On this view, that residue is what education actually amounts to.

The definition is deliberately awkward, because it measures education by what cannot be tested directly. A pupil who scores well may retain little of value, while one who forgets the syllabus entirely may still have been shaped by the discipline of learning it.

The implication is that teaching aimed only at recall misses the point, and that the years spent in a classroom should be judged by the thinker they produce rather than the facts they deposit. A counterview holds that forgotten detail is not wasted, since factual grounding is often what makes later understanding possible.