This essay made him famous, and its publication was the beginning of a remarkable literary career. His principal literary works are his "Confessions," in which he declares that he conceals nothing concerning himself; the "Social Contract," an anti-monarchic work, which many believe incited the French Revolution; "Heloise," a novel over-strained in sentiment and immoral in its teachings, but "full of pathos and knowledge of the human heart"; and "Emile," his greatest work, which contains his educational theories. The "Emile"[123] was an epoch-making book, which excited great interest throughout Europe. It is said that the philosopher Emanuel Kant became so absorbed in reading it that he forgot to take his daily walk. =Pedagogy.=--(_a_) Rousseau's first principle is, "Everything is good as it comes from the hands of the Author of nature; everything degenerates in the hands of man." It follows, then, that education has only to prevent the entrance of evil, and let nature continue the work begun. It is to be a negative, as well as a natural, process. The fallacy of this principle is very forcibly shown by Vogel[124] as follows: "The very first sentence of 'Emile,' that man by nature is good, is a fundamental error; for by nature, that is, from birth, man is neither good nor bad, but morally indifferent. Only when the individual possesses mature self-consciousness does he have a correct idea of good and evil. If man by nature is good, it is inexplicable how evil can originate within him. External things may, indeed, furnish motives to evil, but are never in themselves evil; the evil arises rather from the conduct of the individual toward outside objects. If, then, evil does not come from without, and is not by nature already within the heart, it is impossible that there shall be such a thing as evil." (_b_) The first education is physical and it begins at birth. As the physical wants of the child are natural they should be satisfied, but the clothing should be of such character as not to interfere with the perfect freedom of the body. Great care must be taken to distinguish between the real wants of the child and its passing whims. To gratify the latter because of the crying of the child will tend to form bad habits. In this connection may be taught the first moral lessons. It thus becomes important that the speech, gestures, and expressions of the young child shall be carefully studied. This is the first suggestion of the necessity for child study. The idea was later developed by Pestalozzi and Froebel, and is one of the most important features of recent pedagogical activity.