Simone Weil on St. John Vianney

"Never in any case whatever is a genuine effort of the attention wasted.  It always has its effect on the spiritual plane and in consequence on the lower one of the intelligence, for all spiritual light lightens the mind.
     "If we concentrate our attention on trying to solve a problem of geometry, and if at the end of an hour we are no nearer to doing so than at the beginning, we have nevertheless been making progress each minute of that hour in another more mysterious dimension.  Without our knowing or feeling it, this apparently barren effort has brought more light into the soul.  The result will one day be discovered in prayer. . . . it may very likely be felt in some department of the intelligence. . . . But it is certain that this effort will bear its fruit in prayer.  There is no doubt whatever about that. . . .
". . . Even if our efforts of attention seem for years to be producing no result, one day a light that is in exact proportion to them will flood the soul. . . .  The useless efforts made by the Curé d'Ars, for long and painful years, in his attempt to learn Latin bore fruit in the marvelous discernment that enabled  him to see the very soul of his penitents behind their words and even their silences."

     Simone Weil, "Reflections on the right use of school studies with a view to the love of God," in Waiting for God, trans. Emma Craufurd (New York:  G. P. Putnam's Sons, 1951), 106-108.  Note, however, this qualification:  "If there is a real desire, if the thing desired is really light" (107).
     Cf. Hilary of Poitiers.