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.