ST JOHN OF THE CROSS
All creatures are like crumbs which have fallen from God’s table; and they who go about feeding upon creatures are rightly designated as dogs, and are deprived of the children’s bread, because they refuse to rise from the crumbs of creatures to the uncreated Spirit of their Father. This is precisely why they wander about hungry as dogs. For the crumbs serve more to whet their appetite than to satisfy their hunger. David says of them: “They come back like dogs. / They howl and roam about the city, / They prowl in search of food, / They snarl till they have their fill” (Psalm 58). Here is a peculiarity of a person with appetites: he is always dissatisfied and bitter, like someone who is hungry....
It is plain that the appetites are wearisome and tiring. They resemble little children, restless and hard to please, always whining to their mother for this thing or that, and never satisfied. Just as a man who digs covetously for a treasure grows tired and exhausted, so does he who strives to acquire the demands of his appetites become wearied and fatigued. And even if he does finally obtain them, he is still always weary because he is never satisfied. For after all, he digs leaking cisterns which cannot contain the water that slakes thirst. As Isaiah says: “Just as when a hungry person dreams of eating and wakes up still hungry, or a thirsty person dreams of drinking and wakes up faint, still thirsty...” (Isaiah 29:8).
The appetites are wearisome and tiring because they agitate and disturb, just as wind does with water. And they so upset you that they do not let you rest in any place or thing. Isaiah declares of such a soul: “The wicked are like the tossing sea that cannot keep still” (Isaiah 57:20).
The person seeking satisfaction of desires grows tired, because he is like a famished person who opens his mouth to satisfy himself with air, only to find that instead of being filled, his mouth dries up more, since air is not his proper food....
Just as a lover is wearied and depressed when on a longed-for day his opportunity is frustrated, so are they wearied and tired by all their appetites and their fulfilment, because the fulfilment only causes more hunger and emptiness.