In the confessional, as the priest gives absolution, he says, 'I absolve you of your sins'. He does not say Jesus Christ absolves you of your sins. The priest is acting in the person of Christ, 'In Persona Christi'.
Think about this for a minute, as it is an awesome truth.
During the consecration of the host, the priest says, 'This is MY Body'. He does not say, this is the Body of Christ. The priest is acting in the person of Christ, 'In Persona Christi'.
Again it is almost incomprehensible, that it is possible for any human person to act in the person of Christ. However, it is a teaching of the Church, and is therefore to be believed.
What could be more rewarding to anyone than to know that when we give back to GOD the fruits of the talents He has given to us, we are doing it 'In Persona Christi'?
"Indeed, what I have forgiven, if I have forgiven anything, I have done for your sake's, in the person of Christ." 2Corinthians 2:10