Leviticus 12:1 to Leviticus 13:8
In order to show us that Divine resources made provision in advance for the appearance of sin, Leviticus considers the sacrifices and the priesthood before sin itself. Ch. 11 teaches us to be watchful so as not to be contaminated by uncleanness from without. But evil is not only around us, it is equally within us; our enemy is already inside. Ch. 12 makes us aware of its hereditary character: "Behold, I was shapen in iniquity; and in sin did my mother conceive me." (Psalms 51:5). Adam’s sinful nature has been handed down to all his race; a little new-born child is potentially a sinner before committing any guilty act, and he needs Christ’s sacrifice just as an adult does.
Ch. 13 and 14 deal with leprosy, which always represents sin as defilement. Leprosy: an illness which destroys the body, is contagious, causes fear, deadens the sense of touch and which could not be cured! In God’s eyes, sin presents corresponding features; it expresses itself in actions, in words, alas! even in believers – we know it only too well!
Examples: Miriam – calumny (Numbers 12:10) Gehazi – greed and lies (2 Kings 5:27) Uzziah – spiritual pride (2 Chronicles 26:20)