St. Gregory of Nyssa
Keys, Rock of the Church, Chief of the Apostles, St. Peter
“Peter, the chief of the Apostles, is recalled and the remaining members of the Church are glorified with him for indeed the Church of God is established upon him. This is in accord with the Lord’s words who made him the firm and most solid rock upon which he had built his Church [cf. Mt 16.16ff]. Then we have mention of James, John and [J.105] as sons of thunder whom the Savior had named and who had brought rain clouds; for the gathering of clouds by necessity herald rain. Thus the clouds represent Apostles and prophetic words; although times of preaching differ, nevertheless the laws of true religion are in harmony and one spirit is the source of various gifts….” (Two Homilies Concerning Saint Stephen).
“According to the privilege granted him by the Lord, Peter is that unbreakable and most solid rock upon which the Savior built His church.” (Sermon [A.D 395]). [ή άρραγής καί όχυρωτάτη πέτρα έφ ήν τήν Έκκλησίαν ό Σωτήρ ώκοδόμησε]. (Patrologia Graeca 46, 733).
“through Peter gave to the bishops the keys of the heavenly honors [their prerogative].” (“St. Peter and the Keys of the Kingdom” by Eric Ybarra. PG xlvii, 312c).