Juan Martínez Silíceo was born in Villagarcía de la Torre in 1486, the son of Juan Martínez Guijeno, a poor laborer, and Juana Muñoz.[1] His last name is also given as Guijarro.[1]
Pope Paul IV made him a cardinal priest in the consistory of 20 December 1555.[1] He received the red hat and the titular church of Santi Nereo e Achilleo on 1 February 1556.[1]
He became a renowned mathematician for his time after publishing "Arithmética", firstly printed in Paris and afterwards all across Spain. Apart from "Arithmética" he also publish "Arte calculatorio".[2]
Siliceo successfully fought to impose the limpieza de sangre ("purity of blood") statutes on the Archdiocese of Toledo in order to exclude the Conversos, those Spaniards descended from Jews who had converted to Catholicism, from holding official positions within the Church hierarchy. He used both theological and racist arguments in order to convince Charles V, King of Spain as well as the Pope to approve the exclusionary, racist rules. French scholar of Anti-Semitism, the late Leon Poliakov describes Siliceo as precursor of modern anti-semitic ideas: the idea that Christ appeared among the Jews because of their "perversity" and "as to the Jewish origins of the Mother of God, the theology of Siliceo simply ignored them...anticipating the 'Aryan Christ' of Nazi theology."[3]