This charge was laid upon Esau on the eve of the Passover, and Isaac said to him: "To-night the whole world will sing the Hallel unto God. It is the night when the storehouses of dew are unlocked. Therefore prepare dainties for me, that my soul may bless thee before I die." But the holy spirit interposed, "Eat not the bread of him that hath an evil eye." Isaac's longing for tidbits was due to his blindness. As the sightless cannot behold the food they eat, they do not enjoy it with full relish, and their appetite must be tempted with particularly palatable morsels.