From Jean Cocteau’s Opium: Diary of His Cure (Opium, Journal d’une Désintoxication – though I only have the translation).
Beware of your handwriting, complete your letters, join them together and do not writer t’s which can be mistaken for d’s
The height of inelegance: an illegible signature.
One day, when I was writing an address at Picasso’s house, he looked at me and said with a strange smile: “Oh! you too?” I was in the process of joining thogether the letters in the name that I had just written. Picasso knows everything: naturally he knew that too.