Peter Paul Rubens
St. Ignatius Loyola
Circa 1610-22
Norton Simon Museum, Pasadena, California
Loyola is often pictured in a chasuble looking up as if at a vision. The inscription at the top of the page to which he has opened the book is AD MAJOREM DEI GLORIAM, "To the greater glory of God." This is the motto of the Jesuit order.
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Source: this page at Wikimedia Commons.