Chapters 13 and 14 deal with skin diseases, and other conditions, including leprosy. No doubt God knew what each condition was, but the people's understanding of skin diseases was more basic.

Note the repeated words and phrases; skin, spread, deeper than the skin, priest, unclean. The lesson for us is that leprosy pictures a Christian's sins.

v1: The Lord gave these instructions to both Moses and Aaron. Aaron particularly had the responsibility to put these things into practice.

v2: The leprous man had to go to the priest; just as we go to Christ. Our confidence is that He will accurately identify our sins; we must not fall into the error that denies personal sins (1 John 1.10).

v3: Sin, like leprosy, is more than skin deep. The visible fruit may be only part of the whole. A moment's thought tells us that our sins are not known by all or seen by all, but the Lord sees and knows. We recognise that sins are not just actions and words, but attitudes and thoughts.

v4-5: The need for isolation; Christ was crucified outside the camp, identifying with us. We need sometimes to be away from others, and with the Lord, that we might experience His deep work in our lives, to cleanse and purify.

v6-8: The question was whether the spot or rash has spread; for sin spreads. The priest's role, as explained here, was to declare the person clean or unclean; he did not actually deal with the leprosy. The picture is of justification, in which Christ declares us righteous, for only He can do that (Mark 2.5).

The chapter lists a variety of skin conditions; a boil (v18), a burn, and a reddish-white or white spot (v24), a sore on the head or on the chin (v29), white spots (v38); The principles apply to each condition.

v46: Isolation was necessary because contamination spreads. Sin is particularly serious when it affects others; we should be aware of that danger.

v47-58: The same regulations as applied to people were also applied to clothing.

v55-56: The priest had the job of seeing whether the mildew had continued to spread. It may not have been visible at first; sins may be more dangerous when they are less obvious. Unless sin is exposed, it may not be dealt with.

v57: As in v52, there were specific circumstances when the clothing had to be destroyed. Such is God's grace that He gives opportunity for us to have sin dealt with.

v59: The priest's role was important, as his job was to ensure that the people remained clean, in every way. How grateful we are that Christ, our Great High Priest, is Himself without sin, and always right.