he had taken time to save money, there is no more to be said. When it became his duty to provide for his daughter, between 1763 and 1765, he resolved to sell his library. Through Grimm, Diderot's position reached the ears of the Empress of Russia. Her agent was instructed to buy the library at the price fixed by its possessor, and Diderot received sixteen thousand livres, a sum equal to something more than seven hundred pounds sterling of that day. The Empress added a handsome bounty to the bargain. She requested Diderot to consider himself the custodian of the new purchase on her behalf, and to receive a thousand livres a year for his pains. The salary was paid for fifty years in advance, and so Diderot drew at once what must have seemed to him the royal sum of between two and three thousand pounds sterling--a figure that would have to be trebled, or perhaps quadrupled, to convey its value in the money of our own day. We may wish for the honour of letters that Diderot had been able to preserve his independence. But pensions were the custom of the time. Voltaire, though a man of solid wealth, did not disdain an allowance from Frederick the Great, and complained shrilly because it was irregularly paid at the very time when he knew that Frederick was so short of money that he was driven to melt his plate. D'Alembert also had his pension from Berlin, and Grimm, as we have seen, picked up unconsidered trifles in half of the northern courts. Frederick offered an allowance to Rousseau, but that strange man, in whom so much that was simple, touching, and lofty, mingled with all that was wayward and perverse, declined to tax the king's strained finances.[240]