But it is not necessary to multiply illustrations. Suffice it to say, in conclusion, I hold it to be a most manifest truth, that the general education of a community increases largely its material wealth, both by the direct effect which knowledge has upon individuals in making them individually more productive, and by the increased control which the diffusion of knowledge gives to mankind over the powers of nature. A nation or a state is wisely economical which spends largely and even lavishly upon popular education. XXX. WHAT IS EDUCATION? My last chapter, like the first, begins with a question. Strange to say, no satisfactory definition of education has yet been given, nor has a definition of it often been even attempted. The literature of the subject is copious enough. But writers have busied themselves mainly with details, with methods of teaching, and so forth. A few, of a more philosophical turn of mind, have discussed the principles of the subject, and among these some have undertaken to develop their theories from the true starting-point of a definition. But among all these, from Plato, who was the earliest systematic writer on the subject, to Herbert Spencer, the latest and the most pretentious, not one has given a definition of it which is not open to objection. It may seem presumptuous, perhaps, to undertake again that in which so many have failed. But there can be no harm in making at least an endeavor. What then are some of the elements which enter into our idea of education? To educate is, in the first place, to develop. It is to draw out and strengthen the powers and give them right direction. It is, therefore, something more than merely imparting knowledge. Knowledge is to the child's mind what food is to the body. Each is a means to an end. It is to cause growth. As by the proper use of food and exercise the limbs and muscles expand, and acquire their full and appointed size, symmetry, and strength, so by acquiring and using knowledge of various kinds, the various faculties of the mind attain their full power and proportion. For this reason mainly the pure mathematics and the ancient languages, Latin and Greek, have held their place in almost every course of liberal study, not because the knowledge of these branches is likely to be called for in ordinary professional business, but because the study of these branches is supposed to be particularly adapted to develop and invigorate certain important qualities of the mind. This development of the powers, then, is the first element involved in a just idea of education.