Libro de plata redvzida (Book on the conversion of silver) was published in Lima, Peru, in 1607. This work, by a Spanish-born accountant called Francisco Juan Garreguilla, is a manual for silver merchants, a conversion tool that enabled them to determine the price of a piece of silver by its purity and weight. The first printing press in South America was established in Lima by Antonio Ricardo (circa 1540−1606), an Italian who had worked for a time as a printer with the Jesuits in Mexico City. This book is part of a collection of 39 first editions in the National Library of Peru, produced at the press between 1584 and 1619. The collection was inscribed on the UNESCO Memory of the World Register in 2013. In Latin, Spanish, and several Amerindian languages, these books are an important part of the record of the encounter between two worlds: the Amerindian civilization of the Incas and the European culture represented by the Spanish conquistadors. They are important sources for the study of the dissemination of ideas in the Spanish Empire, including the evangelization process and the diffusion of Catholicism on the one hand and the debate over the indigenous peoples and their condition as human beings on the other. Several of the books provide insights into the political, cultural, and social organization of the vanquished Inca civilization, as well as a record of the Quechua and Aymara languages spoken by the Incas.