These words refer to the mastery of facts and concepts in a given field. Learning is the least formal of these words; it specifically suggests a background of orderly, prescribed instruction and study rather than a spontaneous or self-taught mastery of material: book learning ; the learning required to understand the obscure references of some modern authors. A related use of the word refers to the process of acquiring mastery: patterns of learning in primary-school children. Sometimes the word refers to the sum total of all understanding and wisdom: libraries where the learning of the ages accumulates.

Knowledge is more commonly used in this comprehensive way, referring to all that can be or is known: struggles to increase man’s knowledge of the universe. Knowledge is more than a store of facts in the mind; it includes also the contribution of the mind in understanding data, perceiving relations, elaborating concepts, formulating principles and making evaluations. As applied to a person, knowledge need not refer to information acquired through a formal education, as learning does; rather, knowledge simply points to an acquaintance with facts or an understanding of actions and concepts: a poor knowledge of Greek history.

• She had a better knowledge of human nature than the cleverest psychiatrist, for all his learning .

Knowledge , thus, need not suggest an academic background at all, but can result from observation and experience. In this sense it is similar to the informal term know-how , which refers to special sometimes limited, but always handy, knowledge contrasts most sharply with scholarship , which emphasizes exclusively that aspect of learning pertaining to academic accomplishment. At one level, the word may simply suggest excellent work done in school: students receiving special awards for scholarship . At another level, it refers to care, precision and accuracy in searching out information and presenting facts, implying a mastery of techniques necessary for advanced research in specialized fields: the definitive book on the Medicis, marked by its authoritative mass of data and flawless scholarship .

Erudition refers to the personal mastery of a wide range of specialized knowledge in such a way as to combine both learning and scholarship.

• He was not merely well-informed, but exhibited amazing erudition on every topic of conversation that came up; a Ph.D. candidate’s dazzling display of erudition in his comprehensive exams.

The word suggests a detailed grasp of the most abstruse or arcane points of knowledge . In this it compares with pedantry , which is pejorative word for the same grasp of detail, however obscure. The negative force of the word pedantry , of course, suggests that such details are dogmatically exploited for their own sake as a pharisaical display, without regard for their relevance to refining Ptolemy, while Copernicus and Brahe were altering the whole map of the heavens.