The Gospel for today, Thursday of the first week of Ordinary Time, is Mark 1:40-45, the healing of the leper.
Moved with pity, the Lord wills the cleansing of this kneeling, begging man. He touches this untouchable person and sends him to quietly fulfill the requirements of the Mosaic laws prescribed for ritual cleansing. See that you tell no one, he says.
The man goes and publicizes the event, and the crowds are such that Jesus can no longer openly enter towns, remaining outside in deserted places and people kept coming to him from everywhere.
The man was healed entirely. Though his leprosy was gone, to rejoin community required obedience to the rules and concrete actions. There is something here about sin and reconciliation. Freed from the disease of sin in the sacrament of Reconciliation, we restore our relationship with God. We are then given the freedom to restore right relations with those our sins have affected. Forgiveness comes before penance.
Why did the Lord ask him to remain silent?
The Catena Aurea has this reflection from St. Bede the Venerable:
Now it may well be asked, why our Lord ordered His action to be concealed, and yet it could not be kept hid for an hour? But it is to be observed, that the reason why, in doing a miracle, He ordered it to be kept secret, and yet for all that it was noised abroad, was, that His elect, following the example of His teaching, should wish indeed that in the great things which they do, they should remain concealed, but should nevertheless unwillingly be brought to light for the good of others. Not then that He wished any thing to be done, which He was not able to bring about, but, by the authority of His teaching, He gave an example of what His members ought to wish for, and of what should happen to them even against their will.
Righteous action demands nothing except silence and stillness as place for work. Once given the grace to participate in God’s will on Earth, there is nothing we can add. Seeking earthly glory (or its quieter personal version, which is vanity) moves the focus away from God.