De revolutionibus orbium coelestium have begun work on his new system by that time. Most historians believe that he wrote the "Commentariolus" after his return from Italy, possibly only after 1510. At this time, Copernicus anticipated that he could reconcile the motion of the Earth with the perceived motions of the planets easily, with fewer motions than were necessary in the "Alfonsine Tables", the version of the Ptolemaic system current at the time. In particular, the heliocentric Copernican model made use of the Urdi Lemma developed in the 13th century by Mu'ayyad al-Din al-'Urdi, the first of the Maragha astronomers to develop a non-Ptolemaic
Against the Current: Essays in the History of Ideas published in 1973. In this essay, Berlin explains his theory of a Counter-Enlightenment. Berlin traces the ideology of figures such as Giambattista Vico, from their opposition to enlightenment ideals to the emergence of Romanticism and Existentialism. Against the Current: Essays in the History of Ideas Against the Current: Essays in the History of Ideas (1979) is a collection of essays by 20th century philosopher and historian Isaiah Berlin. The collection was edited by Henry Hardy, and featured an introduction by Roger Hausheer. The book collects previously published essays in which Berlin discusses the thoughts of 20th century ideologic dissenters who