the foreskin, uncleanness, an enemy, a scandal, a heart of stone, the north wind; all this signifies the malignity which is concealed and impressed in the heart of man.
Midrasch Tillim says the same thing and that God will deliver the good nature of man from the evil.
This malignity is renewed every day against man, as it is written, Psalm 37:32: "The wicked watcheth the righteous, and seeketh to slay him"; but God will not abandon him. This malignity tries the heart of man in this life and will accuse him in the other. All this is found in the Talmud.
Midrasch Tillim on Psalm 4:4: "Stand in awe and sin not." Stand in awe and be afraid of your lust, and it will not lead you into sin. And on Psalm 36:1: "The wicked has said within his own heart: Let not the fear of God be before me." That is to say that the malignity natural to man has said that to the wicked.
Midrasch el Kohelet: "Better is a poor and wise child than an old and foolish king who cannot foresee the future." The child is virtue, and the king is the malignity of man. It is called king because all the members obey it, and old because it is in the human heart from infancy to old age, and foolish because it leads man in the way of perdition, which he does not foresee. The same thing is in Midrasch Tillim.
Bereschist Rabba on Psalm 35:10: "Lord, all my bones shall bless Thee, which deliverest the poor from the tyrant." And is there a greater tyrant than the evil leaven? And on Proverbs 25:21: "If thine enemy be hungry, give him bread to eat." That is to say, if the evil leaven hunger, give him the bread of wisdom of which it is spoken in Proverbs 9, and if he be thirsty, give him the water of which it is spoken in Isaiah 55.
Midrasch Tillim says the same thing, and that Scripture in that passage, speaking of the enemy, means the evil leaven; and that, in giving him that bread and that water, we heap coals of fire on his head.
Midrasch el Kohelet on Ecclesiastes 9:14: "A great