Nor is this all. It is well ascertained, from numerous observations, that brunettes develope sooner than their blonde sisters; that those who will grow to be large women are slower than those whose stature will be small; that the dark-haired and black-eyed are more precocious in this respect than the light-haired and blue-eyed; that the fat, sluggish girl is more tardy than the slender, active one; that, in general, what is known as the nervo-bilious temperament is ever ahead of that called the lymphatic or phlegmatic. It is a familiar fact, that it is not a good sign to see this change before the usual average time. It betokens a weakly, excitable, diminutive frame. Hard labor, vigorous, regular muscular exertion--prime health, in other words--never tends to anticipate this epoch, but rather to retard it. With this warning fresh in our ears, let us now rehearse what causes constantly incline unduly to hasten puberty, and thus to forestall wise Nature in her plans for health and beauty. They are of two kinds,--physical and mental. Idleness of body, highly-seasoned food, stimulating beverages, such as beer, wine, liqueurs, and, in a less degree, coffee and tea, irregular habits of sleep,--these are the physical causes of premature development. But the mental causes are still more potent. Whatever _stimulates the emotions_ leads to an unnaturally early sexual life. Late hours, children's parties, sensational novels, 'flashy' papers, love stories, the drama, the ball-room, talk of beaux, love, and marriage,--that atmosphere of riper years which is so often and so injudiciously thrown around childhood,--all hasten the event which transforms the girl into the woman. A particular emphasis has been laid by some physicians on the power of music to awaken the dormant susceptibilities to passion, and on this account its too general or earnest cultivation by children has been objected to. Educators would do well to bear this caution in mind. How powerfully these causes work is evident when we compare the average age of puberty in large cities and in country districts. The females in the former mature from six to eight months sooner than those in the latter. This is unquestionably owing to their mode of life,--physically indolent, mentally over-stimulated. The result, too, is seen with painful plainness in comparing the sturdy, well-preserved farm-wife of thirty, with the languid, pale, faded city lady of the same age. THE CHANGES IT WORKS. Two short years change the awkward and angular girl of fourteen into the trim and graceful maiden of sweet sixteen. Wonderful metamorphosis! The magic wand of the fairy has touched her, and she comes forth a new being, a vision of beauty to bewitch the world. Let us analyze this change.