As birds cannot soar on high with only one wing, neither should the soul persuade herself that she can rise aloft to God by mortification unless it be accompanied by prayer. Mortification without prayer is useless toil, and prayer without mortification is like meat without salt: it soon corrupts. Hence the soul must provide herself with both wings if her flight is to be towards the courts of heaven where her heart ought to find its full content in converse with God.
–Saint Jane Frances de Chantal (1572-1641)