At the age of eighteen he travelled in the United Provinces with Théophile de Viaud, with whom he later exchanged bitter recriminations. His letters written to his acquaintances and to many who held a high position at the French court gained for him a great reputation. Compliments were showered upon him, he became an habitué of the Hotel de Rambouillet. In 1624 a collection of his Lettres was published, and was received with great favour. From the chateau of Balzac, where he had retired, he continued to correspond with Jean Chapelain, Valentin Conrart and others.
In 1634 he was elected to the Academy. He died at Angoulême on the 18th of February 1654. His fame rests chiefly upon the Lettres, a second collection of which appeared in 1636. Recueil de nouvelles lettres was printed in the next year. His letters, though empty and affected in matter, show a real mastery of style, introducing a new clearness and precision into French prose and encouraging the development of the language on national lines by emphasizing its most idiomatic elements. Baizac has thus the credit of executing in French prose a reform parallel to Malhérbe's in verse. In 1631 he published an eulogy of Louis XIII entitled Le Prince; in 1652 the Socrate chrétien, and Aristippe ou de la Cour in 1658.