Second, for all good habits in thought or conduct there are good and real reasons in the nature of things. To leave such habits attached to false opinions is to lessen the weight of these natural or spontaneous reasons, and so to do more harm in the long run than effacement of them seems for a time to do good. Most excellences in human character have a spontaneous root in our nature. Moreover if they had not, and where they have not, there is always a valid and real external defence for them. The unreal defence must be weaker than the real one, and the substitution of a weak for a strong defence, where both are to be had, is not useful but the very opposite. II. It is true, the objector would probably continue, that there is a rational defence for all excellences of conduct, as there is for all that is worthy and fitting in institutions. But the force of a rational defence lies in the rationality of the man to whom it is proffered. The arguments which persuade one trained in scientific habits of thought, only touch persons of the same kind. Character is not all pure reason. That fitness of things which you pronounce to be the foundation of good habits, may be borne in upon men, and may speak to them, through other channels than the syllogism. You assume a community of highly-trained wranglers and proficient sophisters. The plain fact is that, for the mass of men, use and wont, rude or gracious symbols, blind custom, prejudices, superstitions,--however erroneous in themselves, however inadequate to the conveyance of the best truth,--are the only safe guardians of the common virtues. In this sense, then, error may have its usefulness.