Catharinus, Ambrosius, or, more properly, Lancelot Politi, was born at Sienna in 1483. He studied law, and afterwards taught that science in several Italian universities; but in 1521 he entered the Dominican order at Florence, and in 1545 accompanied the cardinal del Monte to the Council of Trent. He became afterwards bishop of Minori in 1546, and archbishop of Conza in 1551. He died at Rome in 1553. As a theologian he stood high for learning, but was much given to controversy, and did not spare either the fathers or the dogmas of his Church in his attacks. His principal works are: Commentaria in epistolas Pauli (Venice, 1551, fol.): — Enarrationes in Genesin (Rome, 1552, fol.). Some of his writings were published under the title Opuscula (1542). — Pierer, Universal. Lexikon, s.v.; Dupin, Eccl. Writers, 16th cent.; Niceron, Memoires, t. 34.