to choose between a life of labour and a life of pleasure, makes election in favour of the former, and thus wins for himself immortal glory, although by the sacrifice of all those enjoyments which, in the estimation of meaner men, are alone worth living for. A short summary of the teaching of the sophists in its principal features will be found under the article Protagoras. Prodicus was identified with this party in so far as he taught for payment, and proposed to teach those useful accomplishments by which men might raise themselves in the world. He seems to have differed from the other sophists in the greater purity and elevation of his moral doctrines. In particular, he is said to have stood opposed to the opinions of Aristippus who, in anticipation of Epicurus, had broached the doctrine that pleasure is the chief end of man. Athens was the head-quarters of Prodicus and the other sophists, although, like them, he itinerated from place to place in quest of pupils.—J. F. F.
PROMOTUS, Ælius, a physician of the Alexandrian school, whose name has been preserved by his works, but of whose history nothing is known. Even the century in which he lived is a matter of conjecture. Villoisin refers him to some period after the time of Pompey the Great; others believe him to have been much earlier. Choulant, on the contrary, would place him in the latter half of the first century of the christian era. It is probable that he is the person mentioned by Galen as Ælius. MSS. of his works exist in various European libraries. One entitled δυναμερον, i. e., "Congeries Medicaminum secundum Loca," is preserved in St. Mark's library, Venice; another, ἰατρικὰ, ζυσικὰ, καὶ αντιπαθητικά, at Leyden; another, περὶ ἰοβόλων καὶ δηλητηριών φαρμάκων, is in the libraries of Rome and Paris.—F. C. W.
PRONY, Gaspard Clair François Marie Riche, Baron de, an eminent French engineer and mathematician, was born at Chamelet in the province of the Lyonnais (department of the Rhone), on the 11th of July, 1755, and died at Asniéres, near Paris, on the 29th of July, 1839. In 1776 he entered the École des ponts et chaussées, where he studied under Perronet, and soon afterwards became the most useful assistant of that famous engineer in many of his most important works. In 1787 Prony entered the corps of government civil engineers (Ingenieurs des ponts et chaussées), and in 1791 rose to the rank of engineer-in-chief, and was intrusted with the direction of the government survey of France. In 1792 he undertook the preparation of an enormous series of logarithmic tables, now kept in the observatory of Paris, in which the logarithms are computed to fourteen, nineteen, and twenty-five places of decimals. This gigantic work he completed in 1794, with the aid of a band of assistant-calculators, most of whom were hairdressers who had been thrown out of work by the change of fashion at the Revolution. In 1784 he became professor of mechanics, and afterwards examiner, at the Polytechnic school, and in 1798 director of the École des ponts et chaussées. In 1795 he became a member of the Academy of Sciences, and in 1817 a member of the Board of longitude. In 1814 he received the order of the legion of honour, in 1828 the title of baron, and in 1835 was made a peer. He was employed in many important works of engineering, especially in the time of Napoleon I , who despatched him several times to Italy in order to plan works of improvement in that country. The results of Prony's inquiries during one of those journeys, are embodied in his "Description of the Pontine Marshes," Paris, 1823. His researches embrace every branch of practical mechanics, and are of the highest value and importance.—W. J. M. R.
PROPERTIUS, Sextus Aurelius, the elegiac poet, was born in Umbria about 50 B.C. His family property was mostly confiscated in the civil wars, and the troubles of those times seem to have had a depressing effect on the poet's genius. He received, however, a good education, and began to write poetry at an early age. The history of his life, so far as it is known to us, is little more than the history of his amours; nor can it even be said with certainty how much of these is fiction. His addresses, however, to his mistress Cynthia seem to bear evident marks of genuine passion, and are classed by Martial with the amatory poems of Catullus. Propertius lived at Rome, and was familiar with the literary society of the capital. Ovid frequently mentions him with regard. Although Propertius early in life attracted by his writings the notice and patronage of Mæcenas, yet in the race for court-favour he seems to have fallen behind his more fortunate rivals, such as Horace and Virgil. He qualified himself, indeed, for the great minister's consideration by the zeal with which he sought to hang all the ornaments of poetry on the false idols of the day, by making vice and voluptuousness graceful, by singing in sounding verse the legends of Roman mythology, and by praising to the skies the glories of Augustus and the virtues of his trusty counsellor. But on all these topics, similar as they are to those which Horace has so delicately recommended to us, we feel sensibly the inferior powers of the less successful competitor. Propertius is deficient in that light touch and exquisitely polished taste which volatilize the sensuality and flattery of Horace. The playfulness of the Sabine poet is that of a lapdog, while the Umbrian reminds us of the pranks of a clumsier and less tolerated quadruped. His elegiac compositions are very inferior in beauty of expression and tenderness of feeling to those of Tibullus and Ovid; his sentiments are often frigid and pedantic, and the meaning is continually overlaid with a cumbrous display of Greek learning. It seems indeed to have been his great ambition to become the Roman Callimachus or Philetas. It must, however, be admitted that his obscurity, so intolerable in an elegiac poet, is in some degree owing to the corrupt state of the text. The year of his death is unknown. The fanciful minuteness of modern criticism has produced a dissertation to show that the disagreeable acquaintance whom Horace vainly tried to shake off in the Via Sacra was no other than Propertius; but this is quite uncertain. Four books of elegies comprise the extant works of Propertius. The best editions are those of Lachmann, Leipsic, 1816, for the text, and Hertzberg, Halle, 1844, for explanatory notes. The edition of Paley in the Bibliotheca Classica is of little value.— G.
PROSPER, of Aquitaine in Gaul, a learned theologian, belonged to the fifth century. In early life he became intimate with one Hilarius, called by way of distinction Hilarius Prosperi. Prosper with his friend was an ardent defender of Augustine's doctrines against the Semipelagians in Southern Gaul. In 426 he wrote to Augustine, informing him of the spread of false doctrine, and requesting the bishop of Hippo to write against it. In 431 he visited Rome to interest Pope Cœlestinus in the controversy, who addressed a letter on the subject to the Gallic bishops. Afterwards he had some connection with Leo I., but its nature is unknown. His death is commonly placed in the year 455. Considering the part he took in the doctrinal development of his day, it is singular that his life should be enveloped in obscurity. He was an able controversialist and good reasoner, very zealous for what he held to be Bible truth. His works are theological, historical, and poetical. Many, however, that have been assigned to him are not his. The best edition is the Benedictine one, Paris, 1711, folio.—S. D.
PROTAGORAS, one of the earliest of the Greek sophists, was born at Abdera in Thrace, about 480 B.C. He is said to have been originally a porter, and to have been relieved from this menial occupation by Democritus. But the story, says Dr. Smith, "seems to have arisen out of the statement of Aristotle that Protagoras invented a sort of porter's knot for the more convenient carrying of burdens." The sophists were a class of teachers and thinkers who made their appearance at the time when the great colonial philosophies, the Ionic Pythagorean, and Eleatic, were on the wane. This was soon after the triumph of the Greek arms over the mighty power of Persia, about the middle of the fifth century B.C. They stood between the older philosophers and Socrates and Plato during a period of great intellectual excitement, of which they were both the effect and the cause. They were the first who took payment for their lessons. They undertook to instruct the rising generations in all useful accomplishments, and particularly in the art of rhetoric; and it is probable that to a large extent they made good their professions.—(For an able account and defence of them see Grote's History of Greece, vol. viii.) But although it may be true that, as practical teachers, the sophists were useful in their generation, and that they have been visited with an indiscriminate vituperation which they do not merit, it is nevertheless certain that their principles were of a false and hurtful tendency, and that they are defensible only on the ground that they represent a crisis through which it was necessary that the human intelligence should pass. The saying of Protagoras, that "man is the measure of the universe," contains the marrow of their philosophy. It meant that our individual judgments and feelings were the standard of the true and false, of the right and wrong; that whatever each man regarded as right was right, and that whatever he regarded as true was true—a doctrine which obviously