_Heat._--Thermometrical influence is much clearer and more evident. Napoleon, who defined man as “a product of the physical atmosphere and the moral atmosphere,” and who suffered from the faintest wind, loved heat so much that he would have fires even in July. Voltaire and Buffon had their studies warmed throughout the year. Rousseau said that the action of the sun in the dog-days aided him to compose, and he allowed the rays of the mid-day sun to fall on his head. Byron said that he feared cold as much as a gazelle. Heine wrote in one of his letters, “It snows; I have little fire in the room, and my letter is cold.” Spallanzani, in the Ionian Islands, found himself able to study for three times as many hours as in misty Pavia.[190] Leopardi confesses in his letters, “My temperament is inimical to cold. I wait and invoke the reign of Ormuzd.” Giusti wrote in the spring, “Inspiration is becoming favourable.... If spring aids me as in all other things....”[191] Paisiello could only compose beneath six quilts in the summer and nine in the winter. Similar facts are told of Varillas, Méry, and Arnaud. Sylvester tells how, when on board the _Invicta_, beneath the vivifying rays of a powerful sun, the method of resolving a multiple equation occurred to him, and he succeeded, without pen or pencil.[192] Lesage, in his old age, became animated as the sun advanced in the meridian, gradually gaining his imaginative power, together with his cheerfulness; as the day declined, his mental activity gradually diminished, until he fell into a lethargy, which lasted to the following day.[193]