Let us say something about fasting, because many, for want of knowing its usefulness, undervalue its necessity, and some reject it as almost superfluous; while, on the other hand where the use of it is not well understood, it easily degenerates into superstition. Holy and legitimate fasting is directed to three ends; for we practice it either as a restraint on the flesh, to preserve it from licentiousness, or as a preparation for prayers and pious meditations, or as a testimony of our humiliation in the presence of God when we are desirous of confessing our guilt before him.
John Calvin