Émile is a novel, but it is didactic in nature, aimed at elucidating key aspects of Rousseau's philosophy, particularly those relating to education. For wealthy Europeans, eighteenth-century education was rigid and often harsh, and emphasized obedience to a tutor as well as rote lessons. Rousseau, on the other hand, thought that education before the teenage years should be essentially "hands-off," nurturing the child's natural curiosity. Similarly, Rousseau believed in cultivating the heart and the spirit before the mind. Contemporary education prepared children to participate in society, and Rousseau wrote extensively on what he saw as the fundamental corruption of human society. As he says in the opening line of the book, "God makes all things good; man meddles with them and they become evil." A proper education would thus avoid corrupting its subjects. The title character, for instance, avoids going to Paris, regarded by Rousseau as a cesspool of corruption, until reaching adulthood, and at that point he has learned enough that he is mortified at what he sees. 

The rationale of this classic of philosophy, in short, is to demonstrate how man could remake his world through education.