Referring to the classical and healthy principles of the pure liberalism, F.A. Hayek offers us, in his book “The Constitution of Liberty”, one of the most beautiful images of a world based on spontaneous order, natural institutional evolution and free market. The first theories on the concept of liberty were developed especially in the 18th century, in England and France, but only the British territory was going to discover the true essence of this theory. In this way, two traditions about the theory of liberty are consolidated: an empirical and unsystematic one and another one that is speculative and rationalistic. The first category is comprised of the principles of a spontaneous order and of an institutional evolution based on economical and social needs, as an answer to concrete situations that arrised unexpectedly. What can be predicted is excluded, the traditions play an important role, customs are the ones that turn into institutions and written laws, but previously recognized by all citizens as a sort of morals. The second category implies planning what will follow in advance. Liberty is present, but within the borders of a plan. Inspired from the visions of the cartesian rationalists, this theory was the one that gained more ground due to immediate explanations, under a clear and seemingly unflawed logic.