A natural education is one that consists not in teaching the child many things, but never letting anything but accurate and clear ideas enter his brain.
Rousseau, in his longing to return to the state of nature, ventures to raise a natural man. Emile (or On Education) is the Corner Stone to Rousseaus Discourse on the Sciences and Arts & Discourse on the Origin and Foundations of Inequality. Rousseaus imaginary pupil, Emile, will get his lessons from nature and not from men. Rousseau is not concerned with teaching Emile numerous facts, but with instructing the child to be able to think for himself.
Emile will have one mentor, Robinson Crusoe. Crusoe is Rousseaus modern natural man. Crusoe is on his island, alone, deprived of the assistance of all the arts, providing nevertheless for his subsistence. Rousseau goes to extremes to create a childhood that is free from habit, and one that provides Emile with the greatest adaptability to his surroundings, whatever they may be, for the rest of his life.
Rousseaus ideas are profound. Though he is far less well known than Marx, Nietzsche, and or Weber, to name a few, his ideas are the basis for the philosophies of these men, who have in return influenced society. Along with Rousseaus Two Discourses, Emile is a must read. (I recommend reading the Discourses before Emile.) However, do not expect Rousseau to tell you everything because he does not spend an extensive time explaining all of the minute details, especially those regarding the first few years of Emiles life. Rather, he says, if you have to be told everything, do not read me.
If you are interested in the foundation of thought for many of the most influential philosophers of modern Europe, then read Emile.