As the gardener, by severe pruning, forces the sap of the tree into one or two vigorous limbs, so should you stop off your miscellaneous activity and concentrate your force on one or a few points.
Most teachers waste their time by asking question which are intended to discover what a pupil does not know whereas the true art of questioning has for its purpose to discover what pupils knows or is capable of knowing.
Each of the professions means a prejudice. The necessity for a career forces every one to take sides. We live in the age of the overworked, and the under-educated; the age in which people are so industrious that they become absolutely stupid.