Catechism of the Catholic Church
“St. Ambrose says about this conversion: Be convinced that this is not what nature has formed, but what the blessing has consecrated. The power of the blessing prevails over that of nature, because by the blessing nature itself is changed…. Could not Christ’s word, which can make from nothing what did not exist, change existing things into what they were not before? It is no less a feat to give things their original nature than to change their nature.”
Source: Catechism of the Catholic Church #1375