At the end of 1300 Manuel Chrysoloras, a man of learning from Constantinople on a diplomatic mission to Florence to obtain help against the Turks, brought the gift of a copy of the Geographia of Ptolemy (2nd century). The treatise, forgotten in Europe, was studied by Arab mathematicians such as al-Idrisi who, at the court of Roger II (1095-1154), had drawn a map of the world in Ptolemaic projection, and had triggered that renewal of science of which Frederick II of Swabia was the guiding spirit.
Ptolemy had summarized the geographical knowledge of his time in his work, giving descriptions, positions and distances of about 8,000 places of the earth; had given names of peoples, climate subdivisions, measurements of the Earth, length of day, etc. And he had also proposed the first geographical projections for representating the sphere on a plane surface.
The "rediscovery" of his work was therefore a key event in the history of cartography, because at the Medici court the Geographia, complete with charts on a trapezoidal projection, was translated into Latin in 1406 and attracted geographers from everywhere, that flocked to Florence to study it and turn it in their respective languages. In 1477 in Bologna the first Ptolemy atlas was published in 500 copies, followed by several editions in the next two centuries, gradually updated with the new geographical discoveries. It 's an ever debated question whether the original work contained maps, or whether the numerous extant "Ptolemaic maps" were only reconstructed during the Renaissance, on the basis of information provided by Ptolemy.