It follows from what has gone before that cerebral fatigue is a most important matter to be reckoned with in all the affairs of life, but especially in education, where the foundations for nervous vigor or weakness are being permanently established, and where relatively little can be accomplished in either intellectual or moral training unless the physical instrument of mind be kept in good repair. It needs no argument to beget the conviction that we should if possible ascertain what circumstances produce fatigue most frequently in the schoolroom, so that they may be ameliorated and their injurious consequences thus avoided. What, then, are the most important causes? It is well to appreciate at the outset that every individual has a certain amount of nervous capital which, when expended, leaves him a bankrupt, and it is of supreme import to him that something should always be kept on the credit side of his account. If we would deal most wisely with a pupil, then, whose activities we are able to direct, we should know just what demands we could make upon his energies without fatiguing him. But we can not hope at the present time and under present conditions to discover with accuracy the fatigue point of each individual, and even if we were able to do so, we would doubtless find it next to impossible to observe it at all times in our teaching, especially in our large graded schools. But we can at any rate adjust our requirements with some degree of accuracy to the average capacity of the whole.