Papal infallibility
Knox has been called "the most learned of all the fathers of that time". He translated the autobiography of Henry Suso in 1865. In 1867 he defended a maximalist interpretation of the doctrine of Papal infallibility, though in a "dry and moderate tone". Appointed Westminster diocesan archivist when Cardinal Manning put the Oratorians in charge of the diocesan archives in 1876, he edited several volumes of English Catholic records.