Peter Louis Morceau de, a celebrated French academician, was born at St Malo in the year 1698, and privately educated there until he attained the age of sixteen, when he was placed under the celebrated professor of philosophy M. le Blond, in the college of La Marche, at Paris. He soon discovered a passion for mathematical studies, and particularly for geometry. In his early years he likewise practised instrumental music with great success, but fixed on no profession till he was twenty, when he entered into the army. He first served in the Gray Musqueteers; but, in the year 1720, his father purchased for him a company of cavalry in the regiment of La Rochegeuyon. He remained only five years in the army, during which time he pursued his mathematical studies with great vigour; and it was soon remarked by Fréret and other academicians, that nothing but geometry could satisfy his active soul and unbounded thirst for knowledge. In the year 1723 he was received into the Royal Academy of Sciences, and read his first performance, which was a memoir upon the construction and form of musical instruments (15th November 1724). During the first years of his admission, he did not wholly confine his attention to mathematics; he dipped into natural philosophy, and discovered great knowledge and dexterity in observations and experiments upon animals. If the custom of travelling into remote climates, like the sages of antiquity, in order to be initiated into the learned mysteries, had still subsisted, no one would have conformed to it with greater eagerness than M. de Maupertuis. His first gratification of this passion was to visit the country which had given birth to Newton; and during his residence at London he became as zealous an admirer and follower of that philosopher as any one of his own countrymen. His next excursion was to Basil in Switzerland, where he formed a friendship with John Bernoulli and his family, which continued till his death. At his return to Paris, he applied himself to his favourite studies with greater zeal than ever. To ascertain how well he fulfilled the duties of an academician, it is only necessary to run over the Memoirs of the Academy from the year 1724 to 1736, in which it appears that he was neither idle nor occupied by objects of small importance. The most sublime questions in geometry and the relative sciences received from his hands that elegance, clearness, and precision, so remarkable in all his writings. In the year 1736 he was sent by the king of France to the polar circle to measure a degree of latitude, in order to ascertain the figure of the earth, accompanied by MM. Clairaut, Camus, Le Monnier, the Abbé Outhier, and Celsius the celebrated professor of astronomy at Upsal. This distinction rendered him so famous, that at his return he was admitted a member of almost every academy in Europe.

In the year 1740 Maupertuis received an invitation from the king of Prussia to go to Berlin, which was too flattering to be refused. His rank amongst men of letters had not wholly effaced his love for his first profession, namely, that of arms. He followed his Prussian majesty into the field, and was a witness of the dispositions and operations which preceded the battle of Mollwitz; but he was deprived of the glory of being present when victory declared in favour of his royal patron, by a singular kind of adventure. His horse having, during the heat of the action, run away with him, he fell into the hands of the enemy, and was at first but roughly treated by the Austrian soldiers, to whom he could not make himself known, from ignorance of their language; but being carried prisoner to Vienna, he received such honours from their imperial majesties as were never effaced from his memory. From Vienna he returned to Berlin; but as the reform of the academy which the king of Prussia then meditated was not yet mature, he went back to Paris, where his affairs called him, and was in 1742 chosen director of the Academy of Sciences. In 1753 he was received into the French Academy, which was the first instance of the same person being at the same time a member of both the academies at Paris. M. de Maupertuis again assumed the character of a soldier at the siege of Friburg, and was pitched upon by Marshal Cogny and the Count d'Argenson to carry the news to the French king of the surrender of that citadel.

He returned to Berlin in the year 1744, when, by the good offices of the queen-mother, a marriage was negotiated and brought about between him and Mademoiselle de Boreck, a lady of great beauty and merit, and nearly related to M. de Boreck, at that time minister of state. This determined him to settle at Berlin, as he was extremely attached to his new spouse, and regarded this alliance as the most fortunate circumstance of his life.

In the year 1746, M. de Maupertuis was declared by his Prussian majesty president of the Royal Academy of Sciences at Berlin, and soon afterwards was honoured with the order of Merit. However, all these accumulated honours and advantages, so far from lessening his ardour for the sciences, seemed to furnish new allurements to labour and application. Not a day passed but he produced some new project or essay for the advancement of knowledge. Nor did he confine himself solely to mathematical studies. Metaphysics, chemistry, botany, polite literature, all shared his attention, and contributed to his fame. At the same time he had, it seems, a strange inquietude of spirit, with a morose temper, which rendered him miserable amidst honours and pleasures. Such a temperament did not promise a very pacific life, and in fact he was engaged in several quarrels. He had a dispute with Koenig the professor of philosophy at Franeker, and another of a more serious kind with Voltaire. Maupertuis had inserted in the volume of Memoirs of the Academy of Berlin for 1746, a discourse upon the laws of motion, which Koenig was not content with attacking, but attributed to Leibnitz. Maupertuis, stung with the imputation of plagiarism, engaged the academy of Berlin to call upon him for his proof, which Koenig failed to produce, and was in consequence struck off the academy, of which he was a member. Several pamphlets appeared on the subject; and Voltaire, for some reason or other, took part against Maupertuis. This is the more unaccountable, because Maupertuis and Voltaire were apparently upon the most amicable terms; and the latter respected the former as his master in the mathematics. Voltaire, however, exerted all his wit and satire against him; and, upon the whole, he was so much transported beyond what was thought right, that he found it expedient in 1753 to quit the court of Prussia.

Maupertuis's constitution had long been considerably impaired by the fatigues of various kinds in which his active mind had involved him; indeed, to the amazing hardships he had undergone in his northern expedition, most of his future bodily sufferings may be traced. The intense sharpness of the air could only be supported by means of strong liquors, which served to increase his disorder, and bring on a spitting of blood, which began at least twelve years before his death. Yet his mind seemed still to possess the greatest vigour; for the best of his writings were produced, and his most sublime ideas developed, during the time of his confinement by sickness, when he was unable to occupy his chair as president at the academy. He took several journeys to St Malo, during the last years of his life, for the recovery of his health; and though he always received benefit by breathing his native air, yet, on his return to Berlin, his disorder returned with greater violence. His last journey to France was undertaken in the year 1757, when, soon after his arrival there, he was obliged to quit his favourite retreat at St Malo, on account of the danger and confusion into which that town was thrown by the arrival of the English in its neighbourhood. From thence he proceeded to Bordeaux, hoping there to meet with a neutral ship to carry him to Hamburg, on his way back to Berlin; but being disappointed in that hope, he went to Toulouse, where he remained seven months. He had then thoughts of going to Italy, in hopes that a milder climate would restore him to health; but finding himself grow worse, he rather inclined towards Germany, and went to Neufchatel, where for three months he enjoyed the conversation of Lord Marischal, with whom he had formerly been much connected. At length he arrived at Basil on the 16th of October 1758, and was there received by his friend Bernoulli and his family with the utmost tenderness and affection. He at first found himself much better there than he had been at Neufchatel; but this amendment was of short duration; for as the winter approached his disorder returned, accompanied by new and more alarming symptoms. He languished here many months, during which he was attended by M. de la Condamine, and died in 1759. The works which he published were collected into four volumes 8vo, published in 1756 at Lyons, where a new and elegant edition was also printed in 1768. These consist of 1. Essai de Cosmologie, first published at Berlin in 1748; 2. Discours sur la Figure des Astres, first published in 1732; 3. Essai de Philosophie Morale, in which he maintains that the sum of evil surpasses that of good; 4. Réflexions Philosophiques sur l'Origine des Langues et la Signification des Mots; 5. Venus Physique, or an Exposition of the System of Generation; 6. Système de la Nature, first published in 1751, and which may be considered as the sequel of the preceding work; 7. Lettres, on various subjects; 8. Éléments de Géographie, published at Paris in 1742, and containing an exposition of the means for determining the figure of the earth; 9. Relation d'un Voyage fait par ordre du Roi au Cercle Polaire, printed at Paris as early as 1738; 10. Relation d'un Voyage au fond de la Lapoche; 11. Letter on the Comet of 1742; 12. Discours Académiques, pronounced in the French and Prussian Academies; 13. Mémoire sur la moindre quantité d'Action; 14. Astronomie Nautique, a work which cried up when it first appeared, but now little read; 15. Parallaxe de la Lune; 16. Mesure du Degré du Nord. Besides these treatises, Maupertuis was the author of a great number of papers, printed partly in the Memoirs of the French Academy of Sciences, and partly in those of the Academy of Berlin.