Some investigators have suggested that the suicidal tendency is dependent on heat; but June is not the hottest month, nor is December the coldest. Durkheim has tested this conjecture by comparing temperatures with suicides in France, Italy, and Prussia. He finds that, in all three of these countries, suicides reach their maximum in June and their minimum in December, while the temperature does not rise to its maximum until July and does not fall to its minimum until January.[19] Moreover, if heat were a predisposing cause of suicide, we should find the suicide rate of Europeans much higher in the tropics than it is in the north temperate zone; but such is not the case. Heat, therefore, as a possible cause, must be eliminated. Other writers, including Dr. Gubski, have called attention to the very close relation between suicide and light. It is true that daylight, if measured by hours, has its minimum in December and its maximum in June, in precise correspondence with the seasonal rates of suicide; but what about the equinoctial periods of March and September? If light be the efficient cause, the tendency to suicide should be as great at the time of the fall equinox as it is at the time of the spring equinox; but this is not the case. Two hundred and seventy-two suicides out of every thousand occur in the vernal equinoctial period and only two hundred and fifteen in the autumnal equinoctial period, and this proportion holds good throughout the whole northern hemisphere. Light, therefore, must also be eliminated. Morselli suggests that suicide is influenced by the first heat of early spring and summer, which "seizes upon the organism not yet acclimated and still under the influence of the cold season." But is there any such thing as winter debility, and, if so, why should it last until June? Many physicians, on the other hand, assert that during the period of early summer the organism, instead of being debilitated, is working at a high tension, that every function of mind and body is then more active than at any other period of the year, and, that, consequently, there is then greater liability to sudden mental and physical collapse. But there is no evidence to show that suicides, generally, are caused by seasonal overtension and subsequent collapse. Goldwin Smith thinks that with the revival of vitality in the spring and early summer "all feelings and impressions become more lively," those that impel to suicide among the rest. But if all the feelings "become more lively," why do not the stimulated sensations of joy and pleasure on a beautiful day in June overcome, or at least evenly balance, the stimulated sensations of suffering and unhappiness? _Influence of Environment on Self-Destruction_