Levítico 11

Levítico 11:3

Hence it is properly decreed in the law that the only animals which are clean and suitable to be eaten by the people of God are those that have horns. For it is well known that those animals that chew the cud and divide the hoof are also those that have horns. So … it is mystically disclosed that the only people who can be incorporated into a spiritual union with the church of God are those who by the strength of their faith prove that they are unconquered in their battles with the vices. — On the Tabernacle 3.11