At the age of eighteen he attracted the notice of the elder Scaliger, and was invited to lecture in the archiepiscopal college at Auch. He afterwards taught Latin at Villeneuve, and then at Bordeaux. Some time before 1552 he delivered a course of lectures in the college of Cardinal Lemoine at Paris, which drew a large audience, King Henry II and his queen being among his hearers.
His success made him many enemies, and he was thrown into prison on a disgraceful charge, but released by the intervention of powerful friends. The same accusation was brought against him at Toulouse, and he only saved his life by timely flight. The records of the town show that he was burned in effigy as a Huguenot and as shamefully immoral (1554).
After a wandering and insecure life of some years in Italy, he received and accepted the invitation of the Cardinal Ippolyte d'Este to settle in Rome in 1559. In 1561 Muret revisited France as a member of the cardinal's suite at the conference between Roman Catholics and Protestants held at Poissy.
He returned to Rome in 1563. His lectures gained him a Europe-wide reputation, and in 1578 he received a tempting offer from the king of Poland to become teacher of jurisprudence in his new college at Cracow. Muretus, however, who about 1576 had taken holy orders, was induced by the liberality of Gregory XIII to remain in Rome, where he died on the 4th of June 1585.
Complete editions of his works: editio princeps, Verona (1727-1730); by D Ruhnken (1789), by CH Frotscher (1834-1841); two volumes of Scripta selecta, by J. Frey (1871); Variae lectiones, by FA Wolf and JH Fasi (1791-1828).
Muretus edited a number of classical authors with learned and scholarly notes. His other works include Juvenilia et poemata varia, orationes and epistolae.
See monograph by C Dejob (Paris, 1881); JE Sandys, Hist. Class. Schol., (2nd ed., 1908), ii. 148-152.