For years Canisius had urged his superiors and had also pleaded at the Council of Trent for the establishment of colleges of writers in various countries to defend the Faith. He was in constant touch with the great printers and publishers of the day, such as Plantin, Cholin and Mayer; he brought out the first reports of foreign missions, and induced the town council of Freiburg to establish a printing-press. All this time he was actively writing, and the list of his publications covers thirty-eight quarto pages in the "Bibliothèque des écrivains de la C. de Jésus." He was commissioned by Pius V to refute the Centuriators of Magdeburg--the society of writers who, under the inspiration of Flacius Illyricus, had undertaken to falsify the works of the early Fathers of the Church, century by century, so as to furnish a historical proof in support of Luther's errors. In 1583 he united in one volume the two books which he had previously issued in 1571 and 1577, styling them "Commentaria de Verbi corruptelis," having in the meantime published the genuine texts of Saints Cyril and Leo.
His "Catechism" was his most famous achievement. It consisted of two hundred and eleven, and later, of two hundred and twenty-two doctrinal questions, and was intended chiefly for advanced students; but there were annexed to it a compendium for children, and another for students of the middle and lower grades. It is recognized as a masterpiece even by Protestant writers such as Ranke, Menzel, Kawerau and others. Two hundred editions of it in one form or another were published during his lifetime in twelve different languages. "I know my Canisius" became a synonym in Germany for "I know my catechism." In brief, he did more than any other man to save Germany for the Church, and he is regarded as another St. Boniface. He died on November 21, 1597 and was beatified by Pius IX on April 17, 1864. The Catechism appears to have been first suggested by Ferdinand I to Le Jay who took up the work enthusiastically. But instead of crowding everything into one volume, he divided it into three: the first, a summa of theology for the university; the second, a volume for priests engaged in the ministry; while the third was for school teachers. He laid the matter before St. Ignatius, who assigned the first part to Laínez and the second to Frusius, then rector of Vienna. But as Frusius died, and Laínez was made General of the Society, Canisius undertook the entire work.