and tobacco are recognisably poisons, so that their consumption has only to be carried far enough to destroy civilisation altogether. Again, take the prevalence of suicide. That, without doubt, is a test of height in civilisation; it means that the population is winding up its nervous and intellectual system to the utmost point of tension and that sometimes it snaps. We should be justified in regarding as very questionable a high civilisation which failed to show a high suicide-rate. Yet suicide is the sign of failure, misery, and despair. How can we regard the prevalence of failure, misery, and despair as the mark of high civilisation? Thus, whichever of the three groups of facts we attempt to measure, it appears on examination almost hopelessly complex. We have to try to make our methods correspondingly complex. Niceforo had invoked co-variation, or simultaneous and sympathetic changes in various factors of civilisation; he explains the index number, and he appeals to mathematics for aid out of the difficulties. He also attempts to combine, with the help of diagrams, a single picture out of these awkward and contradictory tests. The example he gives is that of France during the fifty years preceding the war. It is an interesting example because there is reason to consider France as, in some respects, the most highly civilised of countries. What are the chief significant measurable marks of this superiority? Niceforo selects about a dozen, and, avoiding the difficult attempt to compare France with other countries, he confines himself to the more easily practicable task of ascertaining whether, or in what respects, the general art of civilisation in France, the movement of the collective life, has been upward or downward. When the different categories are translated, according to recognised methods, into index numbers, taking the original figures from the official “Résumé” of French statistics, it is found that each line of movement follows throughout the same direction, though often in zigzag fashion, and never turns back on itself. In this way it appears that the consumption of coal has been more than doubled, the consumption of luxuries (sugar, coffee, alcohol) nearly doubled, the consumption of food per head (as tested by cheese and potatoes) also increasing. Suicide has increased fifty per cent; wealth has increased slightly and irregularly; the upward movement of population has been extremely slight and partly due to immigration; the death-rate has fallen, though not so much as the birth-rate; the number of persons convicted of offence by the courts has fallen; the proportion of illiterate persons has diminished; divorces have greatly increased, and also the number of syndicalist workers, but these two movements are of comparative recent growth.