In the Dominican Breviary, first Vespers of the Holy Apostles Peter and Paul has the following Magnificat antiphon, which retells the famous legend of how, when St Peter thought to flee Rome at the Neronian Persecution, he met the Lord at the outskirts of the City, Who appeared carrying His Cross:.
As so often in confusion Peter had asked the Lord what He was doing during His earthly life, again he asked Him, Lord, whither goest Thou? and received the Divine reply, Peter, I go to be crucified again.
At this implied rebuke, the Apostle turned and returned to Rome, there to endure death as a true witness for Christ, acting as should the disciple sent by so good a Master, taking up the Cross from Him, the Cross that he almost refused, but which the Lord as it were determined to carry for him.
Beatus Petrus Apostolus vidit sibi Christum occurrere, et adorans eum ait: Domine, quo vadis? Venio Romam iterum crucifigi.
(Blessed Peter the Apostle beheld Christ to come to him, and worshipping Him said: Lord, whither goest Thou? I go to Rome to be crucified again.)
This beautiful and significant incident, many times retold down the ages since its first appearance in the apocryphal Acts of Peter (late second century), tells us much about our Christian witness – if we cannot endure, the Lord strengthens us, since in true it is He Who bears our burdens and carries our afflictions. The blood of the Martyrs is the seed of Christians only because it is Christ Who works in them, His members, Who suffers in them, that their mortal labours be of immortal merit for the building up of His Body, the Church.
There still exists a church built on the reputed site of this event.