Résumé :
In 1571, King Philip II purchases for the library of El Escorial a set of 19 manuscripts, from the Greek merchant Andreas Darmarios, once they were examined by the royal secretary Antonio Gracián. In the appraisal of the books Gracián was helped by Calvete de Estrella. This appraisal has been recorded in a document preserved in the Archivo General de Simancas and is published in this paper for the first time in its entirety. Some information about Antonio Gracián is also offered