“If we ask why it is that the world has rejected what was once so universally and so intensely believed, why a narrative of an old woman who had been seen riding on a broomstick, or who was proved to have transformed herself into a wolf, and to have devoured the flocks of her neighbors, is deemed so entirely incredible, most persons would probably be unable to give a very definite answer to the question. It is not because we have examined the evidence and found it insufficient, for the disbelief always precedes, when it does not prevent, examination. It is rather because the idea of absurdity is so strongly attached to such narratives, that it is difficult even to consider them with gravity. Yet at one time no such improbability was felt, and hundreds of persons have been burnt simply on the two grounds I have mentioned. “When so complete a change takes place in public opinion, it may be ascribed to one or other of two causes. It may be the result of a controversy which has conclusively settled the question, establishing to the satisfaction of all parties a clear preponderance of argument or fact in favor of one opinion, and making that opinion a truism which is accepted by all enlightened men, even though they have not themselves examined the evidence on which it rests. Thus, if any one in a company of ordinarily educated persons were to deny the motion of the earth, or the circulation of the blood, his statement would be received with derision, though it is probable that some of his audience would be unable to demonstrate the first truth, and that very few of them could give sufficient reasons for the second. They may not themselves be able to defend their position; but they are aware that, at certain known periods of history, controversies on those subjects took place, and that known writers then brought forward some definite arguments or experiments, which were ultimately accepted by the whole learned world as rigid and conclusive demonstrations. It is possible, also, for as complete a change to be effected by what is called the spirit of the age. The general intellectual tendencies pervading the literature of a century profoundly modify the character of the public mind. They form a new tone and habit of thought. They alter the measure of probability. They create new attractions and new antipathies, and they eventually cause as absolute a rejection of certain old opinions as could be produced by the most cogent and definite arguments.”