Scholar of medieval manuscript illumination and Renaissance art; Princeton University professor. DeWald was descended from Swiss and Alsatian family. He received his undergraduate degree from Rutgers University, New Jersey, before moving to Princeton for his graduate degrees. There, the medievalist in the Department of Art and Archaeology, Charles Rufus Morey introduced him to the study of medieval manuscripts. His first article reflecting Morey's development of the Index of Christian Art at Princeton, was on the iconography of the ascension, published in 1915.

Art critic, librarian and first professor of art historian at Rutgers University. Van Dyke's father, also John van Dyke (1807-1878), was a congressman and supreme court justice of New Jersey, and his mother, Mary Dix Strong, was the daughter of Rutgers mathematician Theodore Strong (1790-1869). His cousin was Henry Van Dyke (1852-1933), the minister, diplomat, and professor at Princeton University. In 1868 the family moved to Minnesota, then just emerging from frontier status. Van Dyke entered Columbia Law School and was admitted to the bar in 1877, although he never practiced.