"For how should he ask for future things, who is not thankful for the past?  Wherefore we ought to give thanks for all things, even for those which seem to be grievous, for this is the part of the truly thankful man.  In the other case the nature of the things demands it; but this springs from a grateful soul, and one earnestly affected toward God.  God acknowledges these prayers, but others He knows not."

-- John Chrysostom, Homily 14 on Philippians