St-Simon, LOUIS DE ROUVEROI, DUKE OF (1675-1755), was a notable diplomatist in the reign of Louis XIV. He had been a soldier, and had fought in Flanders, but diplomacy was a natural outcome of his keen, observant mind. He lived in what has been called the Augustan age of French literature, and his remarkable memoirs are probably the most valuable record of the time in existence. There all his famous contemporaries appear, and many hidden springs of royal action are revealed. Saint-Simon was a courtier, and was entrusted in 1721 with the task, as ambassador to Spain, of arranging a marriage between the Infanta and Louis XV. He was also a member of the council of the Duke of Orleans. The first complete edition of his memoirs appeared in 1830, but there is a later edition in 20 volumes.