unsettles the foundations both of truth and of morality, and opens a wide door to every form of ignorance and licentiousness. But the ultimate principle of the fallacies of the sophists was, their assumption that sensation is the essential attribute of man. Let this be granted and all knowledge of absolute truth, and any other ethics than the morality of selfishness, are rendered impossible. In assuming this as their principle, Protagoras and the sophists appear to have forestalled the whole of the English and French philosophy which in the eighteenth century arose out of the doctrines of Locke, and which has probably still the majority of suffrages in its favour. Socrates and Plato confronted and overthrew the sophistical philosophy by showing that thought (something essentially different from sensation) is the fundamental attribute of man. By showing that ideas (number, resemblance, difference, the good, &c.) were the common property of all intelligence, while sensations were limited and particular, they proved that man is competent to the attainment of what is absolutely and universally true. Occupying this ground, and admitting that man is the measure of the universe in so far as he is a thinking, but not in so far as he is a sensational being, Socrates and Plato overruled the conclusions of Protagoras, and laid the foundations on which a sound doctrine both of absolute truth and of absolute morality might be reared. Protagoras died about 411 b.c., probably at Athens where he chiefly resided, and which was the head-quarters of the sophists generally, as the Greek colonies had been of the philosophers who preceded them.—J. F. F.
PROTOGENES, a famous Greek painter and rival of Apelles, about 340 b.c. He was a native of Caunus in Caria, or of Xanthus in Lycia; but as he lived at Rhodes, the former was more probably the place of his birth. He was originally a ship painter, but eventually was one of the most distinguished of all the Greek painters for the finish of his works, on which he bestowed extraordinary labour. He is said to have devoted seven years to a picture of "Jalysus and his Dog;" and in 304 b.c., when Demetrius was besieging the city of Rhodes, he respected a certain part of the city for fear he might injure this celebrated picture, known to be in that place; the foam of the dog's mouth in this picture delighted the multitude. This "Jalysus" was some centuries later burnt at Rome in the fire which destroyed the temple of peace, where it was preserved. Protogenes was famous for his skill in painting animals. Among his most celebrated works was a "Satyr reposing," with a flute in his hand. In this picture was originally a quail, which attracted to itself so much admiration that the painter, disgusted with the subordinate place given to his satyr, painted it out. Another of his most celebrated pictures was Nausicaa with her maid, riding on mules to the water side to wash their linen, called, from the excellence of the mules, the "Mule picture"—Hemionis. Another was a figure of Paralus, the inventor of war galleys. Protogenes had inserted some small ships of war in the background, to show the character of Paralus. He visited Athens, and while there painted a portrait of Aristotle's mother, and the great philosopher urged him to paint the exploits of Alexander. Protogenes was not at first sufficiently appreciated by the Rhodians; and when Apelles visited that island, seeing this, he offered to buy the works of Protogenes at the price of fifty talents—upwards of £10,000. This opened the eyes of the Rhodians, and they were henceforth proud of their painter. There was preserved in the Palatine gallery at Rome, in the time of Pliny, a panel containing three rival sketches by Apelles and Protogenes, and though but unfinished lines, says Pliny, this work was more admired than any of the finished pictures in the same collection. It was burnt in the fire which consumed the Palatine palace in the time of Augustus.—(Junius, Catalogus Artificum; Wornum, Epochs of Painting.)—R. N. W.
PROUT, Samuel, an eminent painter in water-colours, was born at Plymouth on 17th September, 1783. The passion for drawing was inherent from early childhood. He sketched every kind of picturesque object that he found in the country around his native place; and as he began to find purchasers for his drawings, he extended his sketching rambles into the farther parts of Cornwall and Devon, the bold rocks and rude cottages of the wilder parts of the former county having an especial attraction for him. A more distinct direction was given to his artistic studies by Mr. John Britton the antiquary, who when at Plymouth making notes for the account of Cornwall for the Beauties of England, saw some of young Prout's sketches, and engaged him to make drawings for his work. These drawings gave so much satisfaction that Mr. Prout was induced to remove in 1805 to London. Here he found a ready market at low prices for his water-colour drawings, and was thus enabled to follow out a more thorough course of artistic study than would have been practicable in the country, even had he then deemed it necessary. He now made steady progress, but as yet had not discovered the rich vein of picturesque character which lay hidden in the then almost neglected mediæval architecture, and which he afterwards worked so effectively. At this time his favourite subjects were old fishing villages, boats, and bits of coast scenery, which he treated very effectively, and which were very popular. He also found profitable employment as a teacher, and this led him to acquire the art of etching in order to prepare "lessons" for his pupils to copy. But on the introduction of lithography he was one of the first to recognize its superiority for this purpose; and soon mastering its technicalities, he published a long series of "Studies," "Progressive Lessons," "Rudiments of Landscape," &c., which were found very useful by teachers of landscape-drawing generally, and extended the artist's name very widely. In 1818 Mr. Prout visited Normandy, &c., and this his first continental tour proved so prolific in subjects for his pencil, and so beneficial to his health, which had always been feeble, that henceforth an annual visit to the continent became with him almost a matter of course. It was whilst in Normandy that he commenced in earnest the study of mediæval architecture; and though he never thoroughly mastered its details, he acquired such a degree of power in rendering its time-worn vestiges as in many respects has never been equalled. Prout was a member of the Society of Water-colour Painters, and for a long series of years his works were a leading feature in their annual exhibitions. He adhered in the main faithfully to the old traditions as to methods of working and technical principles of the English school of water-colour painting, and his pictures are among the best examples of that school. His style was large, simple, and effective, but to a great extent conventional. In his later years he published two or three works, with numerous lithographic illustrations executed by himself, in order to explain his views on the practice and principles of art—"Hints on Light, Shade, and Composition," folio, 1838; "The Artists' Sketch-Book;" "Hints for Beginners," &c. He also published two series of lithographic plates in folio, entitled "Facsimiles of Sketches made in Flanders and Germany," and "Sketches in France, Switzerland, and Italy." He died February 10, 1852.—J. T—e.
PROUT, William, a distinguished English chemist and physician, was born in 1786. He studied at the university of Edinburgh, where he graduated as M.D. Afterwards he settled in London, and became a fellow of the Royal College of Physicians. He died April 9, 1850. In chemistry he put forward the hypothesis that the atomic weights or equivalents of the various elementary bodies are multiples of that of hydrogen by a whole number. This view was made known in a paper communicated to the Royal Society of London "On the Relation between the Specific Gravity of Bodies in their Gaseous State to the Weight of their Atoms." It has given rise to much controversy, but appears not to accord with the results of the latest and most accurate experiments. Prout thought it probable that the elements might all turn out to be compounded of oxygen and hydrogen. He showed that the gases may be arranged in two series, in one of which the combining proportion bears the same ratio to that of hydrogen which their specific gravity does to that of the latter body. In the other series the specific gravity is only half as great, while oxygen and fluosilicic acid form an exception. He is the author of one of the Bridgewater Treatises—that on chemistry. In 1822 he produced an essay on the changes which occur in the solid part of the egg during incubation. He was the first chemist who pointed out the true nature and composition of coprolites or phosphorolites. As a physician he is known for his valuable researches on indigestion, and on renal diseases. He was one of the ablest and earliest appliers of chemistry to pathology.—J. W. S.
PRUDENTIUS, Aurelius Clemens, a Latin poet of the fourth century, was born in Spain in 348, either at Cæsar-augusta or Calaguris. Having finished his study of jurisprudence he became an advocate. The Emperor Theodosius invested him twice with the office of imperial lieutenant. It is improbable that he ever held the consulate, or any military dignity; but he seems to have been raised to the rank of patrician. About 405
