the measurements taken according to this method give a new argument in favour of pessimism. However, it is useless to attempt to analyse these figures on which Kowalevsky had to employ the integral calculus, because the principle of his method cannot be supported. As a matter of fact, the rapidity of walking is an index of the degree of excitation, and not of the happy or unhappy condition of the mind. When a person suddenly undergoes a strong impression, either pleasant or unpleasant, he takes to walking actively about in his room, and may even want to go out of doors to walk more quickly. A letter which has been received and which gives some unexpected news, as for instance of the infidelity of a person one loves, or of an inheritance which one did not expect, produces a condition of excitement shown chiefly by rapid walking. Many orators and professors have to make gestures and to walk about in the course of their lectures. A man of science to whom some new idea comes and who wishes to think it out, rises from his chair and begins to walk. But not only on such pleasant occasions, but when one has to face an insult or an act of defiance which makes one very angry, the need to walk actively is felt. It is therefore impossible to utilise records of movements in the study of the pessimistic state of mind. M. Kowalevsky employed still another mode of attacking the problem. He examined the recollection of painful or pleasant impressions. He asked the children of both sexes, whom he was investigating, questions which gave him indications as to whether pleasures or pains made the more lasting impression on the memory, and he registered the answers. The result, which agreed with what had already been obtained by Mr. Colegrove, an American psychologist, was unfavourable to the pessimistic view. He found, in fact, that in the majority of cases (70 per cent.) recollection of pleasant impressions predominated. However, in such investigations there is a facile source of error arising from the condition of mind of those who are being questioned. It is probable that Kowalevsky made his enquiry in school during recreation time, when most of the pupils were free from the boredom of the actual class. When we are happy the tendency exists in us to recall pleasant impressions of the past. If the enquiry had been made during a difficult or wearying lesson, or on children shut up in a hospital, or undergoing punishment, it is probable that the result would have been reversed.