Yet there is in the purest form of liberalism the seed of an insane optimism — a belief that everyone will act well and wisely, or at least not evilly, once he is set free from authority, superstition and adverse circumstance, such that society will progress to ever-greater perfection — an optimism which permits the growth of tyranny if it is not first made sane by the admission that freedom does not by itself teach goodness or halt evil. It is because liberal societies tolerate in the first place ideas, sentiments and movements which are antithetical to freedom that they become so illiberal in the end; for they allow the growth of those things against which they must eventually respond in kind, or be overthrown.
Take a read of the rest of the article; his quote from Jacob Burckhardt is a good one.
The old cliché that we have more to fear from social order than anarchy misses that the seeds of governmental security excess can almost always be found in a failure to provide the physical or material security expected from a state. Authoritarianism is borne out of a failure of a state to secure its people which leads them to turn to someone who promises security at any cost. Either that or the society falls and another mob nation is the result.