And more than once in the course of time, the same theme reappears: among the mystics of the fifteenth century, it has become the motif of the soul as a skiff, abandoned on the infinite sea of desires, in the sterile field of cares and ignorance, among the mirages of knowledge, amid the unreason of the world - a craft at the mercy of the sea's great madness, unless it throws out a solid anchor, faith, or raises its spiritual sails so that the breath of God may bring it to port.