Casanova tells us in his Memoirs that, during his later years at Dux, he had only been able to 'hinder black melancholy from devouring his poor existence, or sending him out of his mind,' by writing ten or twelve hours a day. The copious manuscripts at Dux show us how persistently he was at work on a singular variety of subjects, in addition to the Memoirs, and to the various books which he published during those years. We see him jotting down everything that comes into his head, for his own amusement, and certainly without any thought of publication; engaging in learned controversies, writing treatises on abstruse mathematical problems, composing comedies to be acted before Count Waldstein's neighbours, practising verse-writing in two languages, indeed with more patience than success, writing philosophical dialogues in which God and himself are the speakers, and keeping up an extensive correspondence, both with distinguished men and with delightful women. His mental activity, up to the age of seventy-three, is as prodigious as the activity which he had expended in living a multiform and incalculable life. As in life everything living had interested him so in his retirement from life every idea makes its separate appeal to him; and he welcomes ideas with the same impartiality with which he had welcomed adventures. Passion has intellectualised itself, and remains not less passionate. He wishes to do everything, to compete with every one; and it is only after having spent seven years in heaping up miscellaneous learning, and exercising his faculties in many directions, that he turns to look back over his own past life, and to live it over again in memory, as he writes down the narrative of what had interested him most in it. 'I write in the hope that my history will never see the broad day light of publication,' he tells us, scarcely meaning it, we may be sure, even in the moment of hesitancy which may naturally come to him. But if ever a book was written for the pleasure of writing it, it was this one; and an autobiography written for oneself is not likely to be anything but frank.