Peuskei d’Zimrah-Nisan-Ata Hu-Part Two
But what of the foods prohibited to us by the Torah, such as the forbidden species of cattle, beasts, and fowl? They too perforce possess some spark of holiness, as it is written, “And You preserve them all (Nehemiah 9:6).” Why did God forbid them to us? Is there no need for these too to be selected?
The answer is that God knows that this extraction is beyond mankind’s capability. The holy sparks in these species are too deeply embedded in the Sitra Achra, because their life force is derived from the three impure Kelipot. When a person eats of them, they will not be elevated but instead will overpower his soul, dulling his mind and intellect, and inciting him to lust. That is why God forbade them, and commanded us to select the holy sparks only from that which is permitted.
One may ask how the good will be selected from these material beings. The answer is that once we have done our duty and selected those sparks that we are obligated to extract, then, at the end of days, God will withdraw the sparks from their abodes and all the Kelipot will be nullified. So it was in Egypt: When the end of the exiled king, “and they could not tarry (Exodus 12:39),” all those whose sparks could not be extracted died during the three days of darkness. God will select them at the time of the final redemption in the end of days. “And they shall come who were lost in the land of Assyria; and they who were dispersed in the land of Egypt (Isaiah 27:13).” So too, God forbade certain species, knowing that we could not complete the extraction, and He will do the selection at the end of days. (Rabbi Tzvi Elimelech of Dinov; B’nei Yisaschar, Nisan 4; Derash 8- Part Two)