So much for her Perseverance -- as to her Sense of duty, it evinced itself thus; she liked to learn, but hated to teach; her progress as a pupil depended upon herself, and I saw that on herself she could calculate with certainty; her success as a teacher rested partly, perhaps chiefly, upon the will of others; it cost her a most painful effort to enter into conflict with this foreign will, to endeavour to bend it into subjection to her own; for in what regarded people in general the action of her will was impeded by many scruples; it was as unembarrassed as strong where her own affairs were concerned, and to it she could at any time subject her inclination, if that inclination went counter to her convictions of right; yet when called upon to wrestle with the propensities, the habits, the faults of others, of children especially, who are deaf to reason and, for the most part, insensate to persuasion, her will sometimes almost refused to act; then came in the Sense of duty and forced the reluctant Will into operation.

A wasteful expense of energy and labour was frequently the consequence; Frances toiled for and with her pupils like a drudge, but it was long ere her conscientious exertions were rewarded by anything like docility on their part; because they saw that they had power over her, inasmuch as by resisting her painful attempts to convince, persuade, control; by forcing her to the employment of coercive measures, they could inflict upon her exquisite suffering. Human beings -- human children especially, seldom deny themselves the pleasure of exercising a power which they are conscious of possessing, even though that power consist only in a capacity to make others wretched; a pupil whose sensations are duller than those of his instructor, while his nerves are tougher and his bodily strength perhaps greater, has an immense advantage over that instructor and he will generally use it relentlessly, because the very young, very healthy, very thoughtless know neither how to sympathize nor how to spare.

(Charlotte Brontë, The Professor)