Commentators like John Gill clarify the straightforward, two-part rule for determining which land animals were permissible to eat. For an animal to be considered 'clean,' it had to meet two criteria: 1) it must part the hoof, and 2) it must chew the cud. If an animal met only one of these conditions, like a pig (cloven hoof but doesn't chew the cud), it was deemed unclean.