After relating the Sermon on the Mount, Matthew brings the reader back into the story flow by reiterating how great multitudes followed Jesus. Verse 2 begins, "And behold a leper came. . . ." This statement becomes significant when we consider that no man can come to Christ unless the Father draws him (John 6:44). That the leper came to Christ - amongst a great multitude, no less - was in itself an act of faith in response to what he heard (Romans 10:17). For him to come to Christ as he did, God had to have revealed to him that Christ was the only One who could truly cleanse him and provide him the fresh start he so desired (Matthew 16:15-17). Notice, too, the humility the leper portrays in expressing his understanding of Christ's abilities.
What makes this encounter so interesting is that, under Old Testament law, the leper was completely defiled in his uncleanness. He was to live alone and warn any who would venture near of possible contamination (Leviticus 13:44-46). Albert Barnes, commenting on Leviticus 13:45, notes, "The leper was to carry about with him the usual signs of mourning for the dead. . . . The leper was a living parable in the world of sin of which death was the wages."
In fact, all disease and degeneration are ultimately products of sin and neglect, but none is so gruesomely picturesque of the effect sin has on a person and a community as leprosy. The disease progresses slowly at first, deeply seated in the bones and joints, essentially undetectable until spots appear on the skin. Gradually, these spots grow to cover the entire body. They give the appearance of foul wounds, sore and festering as the body slowly wastes away in a ruinous heap. Parts of the body actually begin falling off, leading eventually to the individual's death.
A leper can live up to fifty years in indescribable misery, as he watches himself die bit by bit, falling to pieces as a hideous spectacle. For the leper of Matthew 8, it was a hopeless predicament; nothing could be done, apart from God's miraculous intervention (Isaiah 1:4-6; Jeremiah 13:23).