"From the moment I read these words, I beheld another world and became another man. Although I have a lively recollection of the impression which they produced upon me, the details have escaped me since I committed them to paper in one of my four letters to M. de Malesherbes. This is one of the peculiarities of my memory which deserves to be mentioned. It only serves me so long as I am dependent upon it. As soon as I commit its contents to paper it forsakes me, and when I have once written a thing down, I completely forget it. This peculiarity follows me even into music. Before I learned it, I knew a number of songs by heart. As soon as I was able to sing from notes, I could not retain a single one in my memory, and I doubt whether I should now be able to repeat, from beginning to end, a single one of those which were my greatest favourites. What I distinctly remember on this occasion is, that on my arrival at Vincennes I was in a state of agitation bordering upon madness. Diderot perceived it. I told him the reason, and read to him the Prosopopoea of Fabricius, written in pencil under an oak-tree. He encouraged me to allow my ideas to have full play, and to compete for the prize. I did so, and from that moment I was lost. The misfortunes of the remainder of my life were the inevitable result of this moment of madness."
January 1, 1970
https://en.wikiquote.org/wiki/Confessions_(Rousseau)