Equally remarkable is the system of general unvarying laws by which this living structure is governed. The first law we notice in human growth is the precedence of physical over mental growth. We observe that physical development, though never separate from mental development, is always in advance of it. This is shown by the wonder and delight with which the parent receives the first sign of awakening intelligence in the young infant, the first smile, the first indication of observation. It is the awakening mind. But every physical function essential to life has been perfectly performed from the first moment of birth as perfectly, according to its wants, as it will ever be performed throughout life. This precedence of physical life continues throughout the whole period of growth, though it strikes us less as the years roll on, and the mind gradually assumes that mastery over the body which should be the condition of adult life. The brain is the last part of the body to cease growth. Every other organ is perfectly formed, every bone consolidated, the physical organization complete, while the mind, with its necessary organ of expression, is still growing. I place this important fact first amongst the rules which govern the human economy because it strikes the key-note of education; and it is only through a thorough appreciation of this principle that we shall beneficially change our present systems of education. Each age has its own special method of existence; thus there are laws for growth, for maturity, for decay. There are the great facts of growth by exercise or use; the necessity of maintaining a just distribution of force amongst the various parts, lest one grow at the expense of another; the alternations of action and rest required in every part of the economy; the varied life of different functions which give to each its individuality and special rule; the varieties of race, of temperament, of individual peculiarities--these will slightly indicate the extent and variety of these unchanging laws by which our human nature is moulded. Their importance may be realized more fully by dwelling for a moment on one or two of them.