The best of the Renaissance writers on education had begun to break away from authority and tradition, and with reason as a guide were groping their way toward a training better suited to the nature and present needs of man than any the past could supply. That their ideas gained currency throughout all Europe and the way was thus prepared for practical reforms is very largely due to the powerful influence exerted by two philosophers, _John Locke_ (1632-1704) and _Jean Jacques Rousseau_ (1712-1778), the former of whom published “Some Thoughts on Education” in 1693, and the latter his “Émile, a Treatise on Education” in 1762. [Illustration: FIG. 7.—John Locke (1632-1704).] Locke was an Oxford graduate and lecturer, had studied medicine and been physician in the household of Lord Ashley, afterwards Earl of Shaftesbury, and his chief work, the “Essay Concerning Human Understanding,” had already appeared (1690). His views, therefore, commanded attention at once, and whatever relates to the physical side of education came with the added weight of special knowledge. The author begins by dwelling at some length upon the hygiene of childhood. “Keep the body in strength and vigor,” he says, “so that it may be able to obey and execute the orders of the mind.... A sound mind in a sound body, is a short but full description of a happy state in this world: he that has these two has little more to wish for; and he that wants either of them will be but little the better for anything else.... He whose mind directs not wisely will never take the right way; and he whose body is crazy and feeble will never be able to advance in it....