December 11, 1872.--A deep and dreamless sleep and now I wake up to the gray, lowering, rainy sky, which has kept us company for so long. The air is mild, the general outlook depressing. I think that it is partly the fault of my windows, which are not very clean, and contribute by their dimness to this gloomy aspect of the outer world. Rain and smoke have besmeared them. Between us and things how many screens there are! Mood, health, the tissues of the eye, the window-panes of our cell, mist, smoke, rain, dust, and light itself--and all infinitely variable! Heraclitus said: “No man bathes twice in the same river.” I feel inclined to say; No one sees the same landscape twice over, for a window is one kaleidoscope, and the spectator another. What is madness? Illusion, raised to the second power. A sound mind establishes regular relations, a _modus vivendi_, between things, men, and itself, and it is under the delusion that it has got hold of stable truth and eternal fact. Madness does not even see what sanity sees, deceiving itself all the while by the belief that it sees better than sanity. The sane mind or common sense confounds the fact of experience with necessary fact, and assumes in good faith that what is, is the measure of what may be; while madness cannot perceive any difference between what is and what it imagines--it confounds its dreams with reality. Wisdom consists in rising superior both to madness and to common sense, and in lending one’s self to the universal illusion without becoming its dupe. It is best, on the whole, for a man of taste who knows how to be gay with the gay, and serious with the serious, to enter into the game of Maïa, and to play his part with a good grace in the fantastic tragi-comedy which is called the Universe. It seems to me that here intellectualism reaches its limit. [Footnote: “We all believe in duty,” says M. Renan, “and in the triumph of righteousness;” but it is possible notwithstanding, “que tout le contraire soit vrai--et que le monde ne soit qu’une amusante féerie dont aucun dieu ne se soucie. Il faut donc nous arranger de maniere à ceque, dans le cas où le seconde hypothèse serait la vraie, nous n’ayons pas été trop dupés.”