CIC 553 Jesus entrusted a specific authority to Peter: “I will give you the keys of the kingdom of heaven, and whatever you bind on earth shall be bound in heaven, and whatever you loose on earth shall be loosed in heaven.”1 The “power of the keys” designates authority to govern the house of God, which is the Church. Jesus, the Good Shepherd, confirmed this mandate after his Resurrection: “Feed my sheep.”2 The power to “bind and loose” connotes the authority to absolve sins, to pronounce doctrinal judgements, and to make disciplinary decisions in the Church. Jesus entrusted this authority to the Church through the ministry of the apostles3 and in particular through the ministry of Peter, the only one to whom he specifically entrusted the keys of the kingdom.

CIC 618 The cross is the unique sacrifice of Christ, the “one mediator between God and men”.4 But because in his incarnate divine person he has in some way united himself to every man, “the possibility of being made partners, in a way known to God, in the paschal mystery” is offered to all men.5 He calls his disciples to “take up [their] cross and follow [him]”,6 for “Christ also suffered for [us], leaving [us] an example so that [we] should follow in his steps.”7 In fact Jesus desires to associate with his redeeming sacrifice those who were to be its first beneficiaries.8 This is achieved supremely in the case of his mother, who was associated more intimately than any other person in the mystery of his redemptive suffering.9
Apart from the cross there is no other ladder by which we may get to heaven.10

CIC 880 When Christ instituted the Twelve, “he constituted [them] in the form of a college or permanent assembly, at the head of which he placed Peter, chosen from among them.”11 Just as “by the Lord’s institution, St. Peter and the rest of the apostles constitute a single apostolic college, so in like fashion the Roman Pontiff, Peter’s successor, and the bishops, the successors of the apostles, are related with and united to one another.”12

CIC 881 The Lord made Simon alone, whom he named Peter, the “rock” of his Church. He gave him the keys of his Church and instituted him shepherd of the whole flock.13 “The office of binding and loosing which was given to Peter was also assigned to the college of apostles united to its head.”14 This pastoral office of Peter and the other apostles belongs to the Church’s very foundation and is continued by the bishops under the primacy of the Pope.

CIC 1429 St. Peter’s conversion after he had denied his master three times bears witness to this. Jesus’ look of infinite mercy drew tears of repentance from Peter and, after the Lord’s resurrection, a threefold affirmation of love for him.15 The second conversion also has a communitarian dimension, as is clear in the Lord’s call to a whole Church: “Repent!”16
St. Ambrose says of the two conversions that, in the Church, “there are water and tears: the water of Baptism and the tears of repentance.”17

CIC 1551 This priesthood is ministerial. “That office. .. which the Lord committed to the pastors of his people, is in the strict sense of the term a service.”18 It is entirely related to Christ and to men. It depends entirely on Christ and on his unique priesthood; it has been instituted for the good of men and the communion of the Church. The sacrament of Holy Orders communicates a “sacred power” which is none other than that of Christ. The exercise of this authority must therefore be measured against the model of Christ, who by love made himself the least and the servant of all.19 “The Lord said clearly that concern for his flock was proof of love for him.”20

1 Mt 16:19.
2 Jn 21:15-17; Cf. 10:11.
3 Cf. Mt 18:18.
4 1 Tim 2:5.
5 GS 22 # 5; cf. # 2.
6 Mt 16:24.
7 I Pt 2:21.
8 Cf Mk 10:39; Jn 21:18-19; Col 1:24.
9 Cf. Lk 2:35.
10 St. Rose of Lima: cf. P. Hansen, Vita mirabilis (Louvain, 1668).
11 LG 19; cf. Lk 6:13; Jn 21:15-17.
12 LG 22; cf. CIC, can. 330.
13 Cf. Mt 16:18-19; Jn 21:15-17.
14 LG 22 # 2.
15 Cf. Lk 22:61; Jn 21:15-17.
16 Rev 2:5, 16.
17 St. Ambrose, ep. 41, 12: PL 16, 1116.
18 LG 24.
19 Cf. Mk 10:43-45; 1 Pet 5:3.
20 St. John Chrysostom, De sac. 2, 4:PG 48, 636; cf. Jn 21:15-17.