What significance do the church fathers attribute to Simon of Cyrene carrying the cross of Christ? Simon of Cyrene is mentioned by name as carrying the cross for Christ in the synoptic Gospels. Are there writings of early Church fathers (ante-Nicene fathers or post-Nicene up to, let's say, 600 AD) who speak to the theological meaning of this event and if so, what theological significance do they give it?
From Thomas Aquinas Catena Aurea, an extract of Origen's comments (There are a number of sites hosting English Translations of the Catena Aurea on the internet.  Here is one such): 


  Origen: Or, as they went out, they laid hold of Simon, but when they drew near
  to the place in which they would crucify Him, they laid the cross upon
  Him that He might bear it. Simon obtained not this office by chance,
  but was brought to the spot by God's providence, that he might be
  found worthy of mention in the Scriptures of the Gospel, and of the
  ministry of the cross of Christ. And it was not only meet that the
  Saviour should carry His cross, but meet also that we should take part
  therein, filling a carriage so beneficial to us. Yet would it not have
  so profited us to take it on us, as we have profited by His taking it
  upon Himself.  


Also in the Catena Aurea, commentary from Venerable Bede (who translated a significant amount of the Church Fathers' writings in his day): 


  Bede: Or, since this Simon is not called a man a Jerusalem, but a
  Cyrenian, (for Cyrene is a city in Libya,) fitly is he taken to mean
  the nations of the Gentiles, which were once foreigners and strangers
  to the covenants, but now by obedience are heirs of God, and joint
  heirs with Christ. Whence also Simon is fitly interpreted ‘obedient’,
  and Cyrene ‘an heir’. But he is said to come from a country place, for
  a country place is called ‘pagos’ in Greek, wherefore those whom we
  see to be aliens from the city of God, we call pagans. Simon then
  coming out from the country carries the cross after Jesus, when the
  Gentile nations leaving pagan rights embrace obediently the footsteps
  of our Lord’s Passion.  


While not exhaustive, this is a sampling of some of the Church Fathers' comments on Simon of Cyrene.  These point to Simon's symbolic position as an example to believers to "pick up your cross and follow me."