Brehm one day gave one of his apes a paper bag with a lump of sugar and a wasp in it. The ape in getting the sugar was stung by the wasp. From that day, whenever Brehm gave that ape, or any other ape in that cage, a paper package, the animal, before opening it, took the precaution to shake the package at his ear and listen to find out whether or not there was a wasp inside.[7] Now, such an act of intelligence implies several inferences. A train of thoughts something like this must have passed through this ape’s mind: ‘Now, if one wasp can sting, so can another; and, if a man can deceive me once by wrapping a wasp in a paper with a lump of sugar, he may try it again; and, if one man will attempt such a thing, so may another; and, if men will attempt it on me, they may attempt it on my friends; so I will warn my friends to look out for those villainous chaps outside.’ These inferences of the ape are the same kind of generalisations exactly as are made by men everywhere in their daily lives. And the common-sense inferences made by ordinary people in their every-day affairs are precisely the same processes of reasoning as those used by scientists and philosophers. Many people, like the character in Moliere’s plays who was surprised and delighted to learn that he had been talking prose all his life, are surprised on hearing for the first time that they use _induction_ and _deduction_ every hour almost of their waking lives. They imagine that philosophers must have some secret and superior way of acquiring their conclusions, different from what ordinary mortals have. ‘But there is no more difference,’ says Huxley, ‘between the mental operations of a man of science and those of an ordinary person than there is between the operations and methods of a grocer weighing out his goods in common scales and the operations of a chemist in performing a difficult and complex analysis by means of his balance and finely graduated weights. It is not that the scales in the one case and the balances in the other differ in the principles of their construction or manner of working; but the beam of the one is set on an infinitely finer axis than the other, and, of course, turns by the addition of a much smaller weight’.[8] And the difference in mental method between the man of learning and the ordinary man or woman is the same as the difference between mature men and children and between men generally and other animals. It is one of _degree_, _not_ of _kind_. The philosopher, the clodhopper, and the ape, all use precisely the same methods of reasoning, differing only in exactness and in the materials of consciousness dealt with.