In the past we were told to do penance as temporal punishment for our sins. The purpose of doing penance is to help us change that pattern. Penance is for growth, not for punishment. Perhaps it would be as well to say that the old conception, replaced by the later choice, is a way of seeing and then seeing again. Externalizing what is within Confession, one aspect of the sacrament which used to receive the greatest emphasis, is now seen as just one step in the total process.
Confession of sin can only be sincere if it is preceded by the process of conversion.
It is actually the external expression of the interior transformation that conversion has brought about in us. It is a much less significant aspect of the sacrament than we made it out to be in the past. Look again at the parable. The father, seeing his son in the distance, runs out to meet him with an embrace and a kiss. When he does, it seems the father hardly listens.