The previous chapter showed us that the world around us is filled with unclean things and we can be contaminated by contact with them. The external character of sin is characterized by the physical elements of certain animals, fish, birds, and insects and all dead things. Sin is all around us. It is everywhere in this lost world.
This is the beginning of the Hebrew calendar as far as we know for certain. But it probably existed from the very beginning. The first month is given the name Abib (Ex. 13:4), which means “spring” or “a young ear of grain.” It overlaps with the modern months of March and April. Most of the months in Scripture did not have names. They are only numbered except for the first one. This changes after they leave Babylon. They adopted the names of the months from the Babylonians who named the months after their gods.