Some of his manuscripts can be downloaded here https://grothendieck.umontpellier.fr/archives-grothendieck/# https://grothendieck.umontpellier.fr/archives-grothe

Some of his manuscripts can be downloaded here https://grothendieck.umontpellier.fr/archives-grothendieck/# https://grothendieck.umontpellier.fr/archives-grothendieck/# but according to this (reliable) radio program [1] he was fascinated by the devil and only wrote about this at the end of his life [1] https://www.franceculture.fr/emissions/la-conversation-scientifique/alexandre-grothendieck-un-mathematicien-qui-prit-la-tangente https://www.franceculture.fr/emissions/la-conversation-scien...