=Theodo´sius Second= became emperor of the Western Roman empire at an early age. His territories were invaded by the Persians, but on his appearance at the head of a large force they fled, losing a great number of their army in the Euphrates. Theodosius was a warm advocate of the Christian religion. He died, aged forty-nine, A.D. 450. =Theophras´tus.= A native of Lesbos. Diogenes enumerates the titles of more than 200 treatises which he wrote. He died in his 107th year, B.C. 288. =Thermop´ylæ.= A narrow Pass leading from Thessaly into Locris and Phocis, celebrated for a battle fought there, B.C. 480, between Xerxes and the Greeks, in which three hundred Spartans, commanded by Leonidas, resisted for three successive days an enormous Persian army. =Thersi´tes.= A deformed Greek, in the Trojan war, who indulged in ridicule against Ulysses and others. Achilles killed him because he laughed at his grief for the death of Penthesilea. Shakspeare, who introduced Thersites in his play of "Troilus and Cressida," describes him as "a deformed and scurrilous Grecian." =The´seus=, king of Athens and son of Ægeus by Æthra, was one of the most celebrated heroes of antiquity. He caught the bull of Marathon and sacrificed it to Minerva. After this he went to Crete amongst the seven youths sent yearly by the Athenians to be devoured by the Minotaur, and by the aid of Ariadne he slew the monster. He ascended his father's throne B.C. 1235. Pirithous, king of the Lapithæ, invaded his territories, but the two became firm friends. They descended into the infernal regions to carry off Proserpine, but their intentions were frustrated by Pluto. After remaining for some time in the infernal regions, Theseus returned to his kingdom to find the throne filled by an usurper, whom he vainly tried to eject. He retired to Scyros, where he was killed by a fall from a precipice. =Thes´pis.= A Greek poet of Attica, supposed to be the inventor of tragedy, B.C. 536. He went from place to place upon a cart, on which he gave performances. Hence the term "Thespians" as applied to wandering actors. =The´tis.= A sea deity, daughter of Nereus and Doris. She married Peleus, their son being Achilles, whom she plunged into the Styx, thus rendering him invulnerable in every part of his body except the heel by which she held him. =This´be.= A beautiful girl of Babylon, beloved by Pyramus. =Thrasybu´lus.= A famous general of Athens, who, with the help of a few associates, expelled the Thirty Tyrants, B.C. 401. He was sent with a powerful fleet to recover the Athenian power on the coast of Asia, and after gaining many advantages, was killed by the people of Aspendos. =Thucid´ydes.= A celebrated Greek historian born at Athens. He wrote a history of the events connected with the Peloponnesian war. He died at Athens in his eightieth year, B.C. 391.