From Question 93 of Ambrosiaster, Questions on the Old and New Testaments:
When the Lord, a few days after his resurrection, breathes on his apostles and says to them, "Receive the Holy Spirit," (Jn. 20:22) He communicates to them the ecclesiastical power. As in the exercise of the powers conferred by the Lord, everything is done by the Holy Spirit, when he gives them the rule and the form of this divine institution, he says to them: "Receive the Holy Spirit.” And to show that it is in fact the power conferred on the Church, he adds: "He whose sins you have retained will be withheld from him, and to whom you have forgiven them, they will be forgiven.” This insufflation is therefore a grace which is communicated by tradition to those who are ordained, and which impresses them with a more impressive and more sacred character, which is why the Apostle says to Timothy: "Do not neglect the grace which is in you, and given to you with the laying on of the hands of the priests." (1 Tim. 4:14) This is what the Savior had to do once, so that it was well established in the Church that the transmission of this power could not take place without the Holy Spirit. Just as the Savior wanted to give in his person a visible example that the Holy Spirit was given after baptism to all who believed in him; so he wanted to give us here a definite proof that the transmission of ecclesiastical power was inseparable from the infusion of the Holy Spirit. The apostles, like the prophets, have the power to perform miracles in the very presence of the Lord. We therefore see in the person of the apostles three different forms of ministry conferred upon them by the Holy Spirit. The first is ecclesiastical power to regenerate the faithful and to fulfill the other duties of the sacred ministry. The second, which was given at Pentecost, is general, for it is not only on the apostles, but on all the faithful, that the Holy Spirit descended. The third was given to the apostles alone, to perform miracles and wonders until the seeds of faith which they shed in hearts were sufficiently developed. These seeds of faith were the wonders performed by the apostles. God established them as the pontiffs of truth, to testify by the miracles and wonders they performed that our faith was according to reason. Indeed, what stronger proof of the truth than a miracle? This is what falsifies all the philosophical systems of the earth, is that they are but a tissue of vain words, without the support of the testimony of the miracle which would testify the immutable truth of their doctrine. The Holy Spirit is therefore generally given to all the faithful, in whose soul it remains as a proof that they are the sons of God. On the contrary, are they miracles and wonders to be done? The Holy Spirit does not abide in man; he comes into him when he is called, he inspires what is necessary, and withdraws. It is the same in the transmission of sacred powers or in ordination; grace is external, and interior help is given only to souls full of faith. (pp. 240-42)
