Lastly, we must not forget that the candidate himself is a necessary and irreplaceable agent in his own formation: All formation, priestly formation included, is ultimately a self-formation. No one can replace us in the responsible freedom that we have as individual persons. And so, the future priest also, and in the first place, must grow in his awareness that the agent par excellence of his formation is the Holy Spirit, who by the gift of a new heart configures and conforms him to Jesus Christ the good shepherd. In this way the candidate to the priesthood will affirm in the most radical way possible his freedom to welcome the moulding action of the Spirit. But to welcome this action implies also, on the part of the candidate, a welcome for the human "mediating" forces which the Spirit employs. As a result, the actions of the different teachers become truly and fully effective only if the future priest offers his own convinced and heartfelt cooperation to this work of formation.