PHILIPPE DE, Seigneur Duplessis Marly, was born at Buhy or Bishuy, in Upper Normandy, in France, in 1549, and was educated at Paris. He made a rapid progress in the belles lettres, in the learned languages, and in theology, which was then thought a prodigy in a gentleman. At first he was destined for the church; but the principles of Calvinism, which he had imbibed from his mother, effectually excluded him from the ecclesiastical preferments to which, by his interest, abilities, and birth, he would have been entitled. After the horrible massacre of St Bartholomew, Philippe de Mornay made the tour of Italy, Germany, England, and the Low Countries; and he was equally improved and delighted by his travels. Mornay afterwards joined the king of Navarre, at that time leader of the Protestant party, and since so well known by the name of Henry IV. This prince sent Mornay, who employed his whole abilities, both as a soldier and a writer, in defence of the Protestant cause, to conduct a negotiation with Elizabeth queen of England; and left him wholly to his own discretion in the management of that business. He was successful in almost every negociation, because he conducted it like an able politician, and not in a spirit of intrigue. He tenderly loved Henry IV, and spoke to him upon all occasions as to a friend. When he was wounded at Aumale, he wrote to him in these words: "Sire, You have long enough acted the part of Alexander, it is now time you should act that of Caesar. It is our duty to die for your majesty. It is glorious for you, Sire, that I dare venture to tell you it is your duty to live for us." This faithful subject did everything in his power to raise Henry to the throne; but when he deserted the Protestant faith, he reproached him in the bitterest manner, and retired from court. Yet Henry still loved him, and was extremely affected with an insult which he received in 1597, when one Saint Phal beat him severely with a cudgel, and left him on the ground for dead. Mornay demanded justice from the king, who gave him the following answer, a proof as well of his spirit as of his goodness of heart. "Monsieur Duplessis, I am exceedingly offended at the insult you have received; and I sympathize with you both as your sovereign and your friend. In the former capacity, I shall do justice to you and to myself; and had I sustained only the character of your friend, there are few perhaps who would have drawn their sword or sacrificed their life more cheerfully in your cause. Be satisfied, then, that I will act the part of a king, a master, and a friend." Mornay's knowledge, probity, and valour, made him the soul of the Protestant party, and procured him the contemptuous appellation of the Pope of the Huguenots. He defended their doctrines both by speech and writing. One of his books, on the Iniquity of the Mass, having stirred up the Catholic divines, he refused to make any reply to their censures and criticisms except in a public conference. This was accordingly appointed to be held in the year 1600, at Fontainebleau, where the court then was. The two champions were, Duperron bishop of Evreux, and Mornay. After a great many arguments and replies on both sides, the victory was adjudged to Duperron. He had boasted that he would point out to the satisfaction of everyone five hundred errors in his adversary's book, and he partly kept his word. The Calvinists did not fail to claim the victory on this occasion, and they still continue to do so. But this conference, instead of putting an end to the differences, was productive of new quarrels amongst the controversialists, and of much profane wit amongst the libertines. A Huguenot minister, who was present at the conference, observed with great concern to a captain of the same party: "The bishop of Evreux has already driven Mornay from several strongholds." "No matter," replied the soldier, provided he does not drive him from Saumur." This was an important place on the river Loire, of which Duplessis was governor, and whither he retired, his attention being constantly occupied in defending the Huguenots, and in making himself formidable to the Catholics. When Louis XIII. was making preparations against the Protestants, Duplessis wrote him a letter, dissuading him from such a measure. After employing the most plausible arguments, he concludes by observing, that to make war on the subject, is an indication of weakness in the government. "Authority," says he, "consists in the quiet submission of the people, and is established by the prudence and justice of the governor. Force of arms ought never to be employed except in repelling a foreign enemy. The late king would have sent the new ministers of state to learn the first elements of politics, who, like unskilful surgeons, would apply violent remedies to every disease, and advise a man to cut off an arm when his finger aches." But these remonstrances produced no other effect than the loss of the government of Saumur, of which he was deprived by Louis XIII. in 1621. He died two years afterwards, on the 11th of November 1623, aged seventy-four, in his barony of La Foret-sur-Seure, in Poitou.

The following is a list of his works: 1. Un Traité de l'Eucharistie, 1604, in folio; 2. Un Traité de la Vérité de la Religion Chrétienne, 8vo; 3. A book entitled La Mystère d'Iniquité, 4to; 4. Un Discours sur le Droit prétends par ceux de la maison de Guise, 8vo; 5. Curious and interesting Memoirs from the year 1572 to 1629, four vols. 4to, valuable; 6. Letters, which are written with great spirit and good sense. David des Liques has published a life of De Mornay, in a quarto volume, which is more interesting for the matter than the style.