Philip Caraman, C.C. Martindale: A Biography
(London: Longmans, 1967), p. 99 (on teaching at Stonyhurst College):
After his first class he was appalled by the low standard of Jesuit teaching at the time. He found that his pupils could not scan ordinary Latin verse, whereas at Harrow, at the same age, they would have been set to write Greek epigrams, and quite possibly in dialect. But he was quick to see the potentialities of his small class. He tutored them individually and strove to make them think. Early on he set his class the Benediction hymn, O salutaris hostia, to render as an unseen. Two boys translated hostia as enemy, and half the rest thought that it meant one who invited guests. Already he reflected that sheer ignorance was at the root of many apostasies. Latin prayers were not understood, and consequently much of the services held no meaning for the boys.
Hat tip: Ian Jackson.