LAETUS, JULIUS POMPONIUS [Giulio Pomponio Leto], (1425-1498), Italian humanist, was born at Salerno. He studied at Rome under Laurentius Valla, whom he succeeded (1457) as professor of eloquence in the Gymnasium Romanum. About this time he founded an academy, the members of which adopted Greek and Latin names, met on the Quirinal to discuss classical questions and celebrated the birthday of Romulus. Its constitution resembled that of an ancient priestly college, and Laetus was styled pontifex maximus. The pope (Paul II.) viewed these proceedings with suspicion, as savouring of paganism, heresy and republicanism. In 1468 twenty of the academicians were arrested during the carnival; Laetus, who had taken refuge in Venice, was sent back to Rome, imprisoned and put to the torture, but refused to plead guilty to the charges of infidelity and immorality. For want of evidence, he was acquitted and allowed to resume his professorial duties; but it was forbidden to utter the name of the academy even in jest. Sixtus IV. permitted the resumption of its meetings, which continued to be held till the sack of Rome (1527) by Constable Bourbon during the papacy of Clement VII. Laetus continued to teach in Rome until his death on the 9th of June 1498. As a teacher, Laetus, who has been called the first head of a philological school, was extraordinarily successful; in his own words, like Socrates and Christ, he expected to live on in the person of his pupils, amongst whom were many of the most famous scholars of the period. His works, written in pure and simple Latin, were published in a collected form (Opera Pomponii Laeti varia, 1521). They contain treatises on the Roman magistrates, priests and lawyers, and a compendium of Roman history from the death of the younger Gordian to the time of Justin III. Laetus also wrote commentaries on classical authors, and promoted the publication of the editio princeps of Virgil at Rome in 1469.
See The Life of Leto by Sabellicus (Strassburg, 1510); G. Voigt, Die Wiederbelebung des klassischen Alterthums, ii.; F. Gregorovius, Geschichte der Stadt Rom im Mittelalter, vii. (1894), p. 576, for an account of the academy; Sandys, History of Classical Scholarship (1908), ii. 92.
LAEVIUS (? c. 80 B.C.), a Latin poet of whom practically nothing is known. The earliest reference to him is perhaps in Suetonius (De grammaticis, 3), though it is not certain that the Laevius Milissus there referred to is the same person. Definite references do not occur before the 2nd century (Fronto, Ep. ad M. Caes. i. 3; Aulus Gellius, Noct. Att. ii. 24, xii. 10, xix. 9; Apuleius, De magia, 30; Porphyrion, Ad Horat. carm. iii. 1, 2). Some sixty miscellaneous lines are preserved (see Bährens, Fragm. poët. rom. pp. 287-293), from which it is difficult to see how ancient critics could have regarded him as the master of Ovid or Catullus. Gellius and Ausonius state that he composed an Erotopaegnia, and in other sources he is credited with Adonis, Alcestis, Centauri, Helena, Ino, Protesilaudamia, Sirenocirca, Phoenix, which may, however, be only the parts of the Erotopaegnia. They were not serious poems, but light and often licentious skits on the heroic myths.
See O. Ribbeck, Geschichte der römischen Dichtung, i.; H. de la Ville de Mirmont, Étude biographique et littéraire sur le poète Laevius (Paris, 1900), with critical ed. of the fragments, and remarks on vocabulary and syntax; A. Weichert, Poëtarum latinorum reliquiae (Leipzig, 1830); M. Schanz, Geschichte der römischen Litteratur (2nd ed.), pt. i. p. 163; W. Teuffel, Hist. of Roman Literature (Eng. tr.), § 150, 4; a convenient summary in F. Plessis, La Poésie latine (1909), pp. 139-142.
LAEVULINIC ACID (β-acetopropionic acid), C5H8O3 or CH3CO·CH2·CH2·CO2H, a ketonic acid prepared from laevulose, inulin, starch, &c., by boiling them with dilute hydrochloric or sulphuric acids. It may be synthesized by condensing sodium acetoacetate with monochloracetic ester, the acetosuccinic ester produced being then hydrolysed with dilute hydrochloric acid (M. Conrad, Ann., 1877, 188, p. 222).
It may also be prepared by heating the anhydride of γ-methyloxy-glutaric acid with concentrated sulphuric acid, and by oxidation of methyl heptenone and of geraniol. It crystallizes in plates, which melt at 32.5-33° C. and boil at 148-149° (15 mm.) (A. Michael, Jour. prak. Chem., 1891 [2], 44, p. 114). It is readily soluble in alcohol, ether and water. The acid, when distilled slowly, is decomposed and yields α- and β-angelica lactones. When heated with hydriodic acid and phosphorus, it yields n-valeric acid; and with iodine and caustic soda solution it gives iodoform, even in the cold. With hydroxylamine it yields an oxime, which by the action of concentrated sulphuric acid rearranges itself to N-methylsuccinimide [CH2·CO]2N·CH3.