Simplify the following text for a Grade 14 native English-speaking person.
Original: Much of what is known about him comes from the book Libro de descripciÃ n de verdaderos retratos de illustres y memorables varones ( Book of the Description of the True Portraits of Illustrious and Memorable Men ) , which was written in 1599 by Francisco Pacheco .
Simplified: Much of what is known about him comes from Libro de descripciÃ n de verdaderos retratos de illustres y memorables varones ( Book of the Description of the True Portraits of Illustrious and Memorable Men ) ( 1599 ) by Francisco Pacheco .