A bound person cannot run. Nor can the mind, which works like a slave for a certain passion, be able to offer a true prayer, because it is dragged around and wanders here and there on account of impassioned thoughts and cannot remain undisturbed. You will not be able to pray clearly if you are preoccupied with material things and are agitated by incessant cares, because prayer implies riddance of every care.
–Saint Nilus of Sinai (d. 430)