In this article, I analyse the texts in which Joseph Ratzinger deals with biological evolution, particularly in the context of the compatibility between faith in creation and acceptance of the theory of evolution. His first writings on the topic, until 1979, contain the most elaborate and deepest theological and philosophical insights, with a defence of the compatibility between faith in creation and the theory of evolution when the boundaries of their respective explanatory frameworks are respected. At the beginning of the 1980s, still at the philosophical level, Ratzinger engages with the work some atheist scientists who try to portray evolution as a "first philosophy". The 1999 lecture at the Sorbonne University marks the beginning of a period in which he criticizes some technical aspects of the theory of evolution, a position that seems to have been prompted by contacts with anti-evolution German intellectuals in the previous years. After the 2006 meeting of the Schulerkreis in Castel Gandolfo, in which his criticism of evolution reaches its climax, his references to the topic were few and he returned to the philosophical ideas expressed in his earlier writings, stressing that the intrinsic rationality and inner logic of the cosmos point to a creating Reason.