Mercurio López Casillas, a passionate bookseller, comes from a family of 13, 9 of whom share his passion for books. He has devoted 70 years to purchase and sell them. His father taught them discipline and a love of books. When an important book was brought to the house, he would get them all together and have them look at the book as it was very old or because it was a special edition, then would sell it. His own testimony tells how his father would take them to the shop every Sunday from seven in the morning until five in the afternoon.
The López Casillas brothers now have 25 bookshops that together are home to over one million volumes, whose history dates back to the decade of the 30s, when Nicolás Casillas, the father changed his craft in Tepito, to engage book sale.
He likes to collect some books, in fact has three collections: One of caricatures from the nineteenth century to date, another one of illustrated books of the twentieth century and one more of eighteenth and nineteenth century illustrated books. He has an outstanding collection of cartoons by José Guadalupe Posada.