only seen what old prepossessions inspired them to see, and were blind to all that would have been fatal to the prepossessions. 'It is beyond all question or dispute,' says Voltaire, 'that magic words and ceremonies are quite capable of most effectually destroying a whole flock of sheep, if the words be accompanied by a sufficient quantity of arsenic.' Sorcery has no doubt been exploded--at least we assume that it has--but the temper that made men attribute all the efficacy to the magic words, and entirely overlook the arsenic, still prevails in a great host of moral and political affairs, into which it is not convenient to enter here. The stability of a government, for instance, is constantly set down to some ornamental part of it, when in fact the ornamental part has no more to do with stability than the incantations of the soothsayer. You have heard, again, that for many generations the people of the Isle of St. Kilda believed that the arrival of a ship in the harbour inflicted on the islanders epidemic colds in the head, and many ingenious reasons were from time to time devised by clever men why the ship should cause colds among the population. At last it occurred to somebody that the ship might not be the cause of the colds, but that both might be the common effects of some other cause, and it was then remembered that a ship could only enter the harbour when there was a strong north-east wind blowing. However faithful the observation, as soon as ever a man uses words he may begin at that moment to go wrong. 'A village apothecary,' it has been said, 'and if possible in a still greater degree, an experienced nurse, is seldom able to describe the plainest case without employing a phraseology of which every word is a theory; the simplest narrative of the most illiterate observer involves more or less of hypothesis;'--yet both by the observer himself and by most of those who listen to him, each of these conjectural assumptions is treated as respectfully as if it were an established axiom. We are supposed to deny the possibility of a circumstance, when in truth we only deny the evidence alleged for it. We allow the excellence of reasoning from certain data to captivate our belief in the truth of the data themselves, even when they are unproved and unprovable. There is no end, in short, of the ways in which men habitually go wrong in their reasoning, tacit or expressed. The greatest boon that any benefactor could confer on the human race would be to teach men--and especially women--to quantify their propositions. It sometimes seems as if Swift were right when he said that Mankind were just as fit for flying as for thinking.