It is told, that in the art of education he performed wonders; and a formidable list is given of the authors, Greek and Latin, that were read in Aldersgate-street, by youth between ten and fifteen or sixteen years of age. Those who tell or receive these stories should consider that nobody can be taught faster than he can learn. The speed of the horseman must be limited by the power of his horse. Every man that has ever undertaken to instruct others, can tell what slow advances he has been able to make, and how much patience it requires to recall vagrant inattention, to stimulate sluggish indifference, and to rectify absurd misapprehension.

Samuel Johnson, “John Milton”

The greatest man of letters in English continually reminds us in his essays and in Boswell's Life that we need to expect an awful lot of resistance to learning, and that he himself, Dr. Samuel Johnson (who had single-handedly composed a dictionary in seven years) lived full of “vagrant inattention” and “sluggish indifference” – though not of “absurd misapprehension”.