The thirst for something other than what we have…to bring something new, even if it is worse, some emotion, some sorrow; when our sensibility, which … - Marcel Proust

The inertia of the mind urges it to slide down the easy slope of imagination, rather than to climb the steep slope of introspection.

...infirmity alone makes us take notice and learn, and enables us to analyse mechanisms of which otherwise we should know nothing. A man who falls straight into bed night after night, and ceases to live until the moment when he wakes and rises, will surely never dream of making, I don't say great discoveries, but even minor observations about sleep. He scarcely knows that he is asleep. A little insomnia is not without its value in making us appreciate sleep, in throwing a ray of light upon that darkness. An unfailing memory is not a very powerful incentive to the study of the phenomena of memory.

L'adultère introduit l'esprit dans la lettre que bien souvent le mariage eût laissée morte.