V.21-45 The miracles we read of here are not simply a sign and proof of His power, but also were a demonstration of His tender love and goodness.
V.40-45 The leper knew of the Lord’s power, but did not know if He was willing to heal him. Jesus shows His compassion. The power and willingness are freely shown to the poor leper — a picture of sin which contaminates all who are touched — and Jesus touches him. But Jesus is not contaminated.
V.44 Only when we go through an experience of His love and grace is our heart really drawn to Him, and our lips opened to tell others.