That prayer has great power which a person makes with all his might.

It makes a sour heart sweet, a sad heart merry, a poor heart rich, a foolish heart wise,
a timid heart brave, a sick heart well, a blind heart full of sight, a cold heart ardent.

It draws down the great God into the little heart;
it drives the hungry soul up into the fullness of God;
it brings together two lovers, God and the soul,
in a wondrous place where they speak much of love.

–  Mechthild of Magdeburg