To what extent did Isaiah understand his own prophecies? Consider Isaiah 53:4-6 (NIV), which is commonly interpreted as a prophecy that the Messiah would die for the sins of the world:


  4Surely he took up our pain
  &nbsp;&nbsp; and bore our suffering,
  yet we considered him punished by God,
  &nbsp;&nbsp; stricken by him, and afflicted.
  5But he was pierced for our transgressions,
  &nbsp;&nbsp; he was crushed for our iniquities;
  the punishment that brought us peace was on him,
  &nbsp;&nbsp; and by his wounds we are healed.
  6We all, like sheep, have gone astray,
  &nbsp;&nbsp; each of us has turned to our own way;
  and the LORD has laid on him
  &nbsp;&nbsp; the iniquity of us all.


It seems apparent that the majority of Jews at the time, did not interpret this passage (and others) to mean that Jesus was the Messiah, until after Christ died.  This seems to be common with many (maybe most or all) Biblical prophecies: There is sufficient detail to identify once an event has occurred, but not sufficient detail to predict when a prophesied event will occur.

So my question:  Did Isaiah understand his own prophecies, in the sense that we do today?  Would Isaiah, for instance, have known that the Messiah would die for the sins of the world? If Isaiah had met Christ before His death, would he have realized he was the Messiah?

Or were Isaiah's own words enigmatic to him as they were to the rest of the world, prior to the fulfillment of the prophecies?
Peter gives us some insight into this:


  10 Concerning this salvation, the prophets, who spoke of the grace
  that was to come to you, searched intently and with the greatest care,
  11 trying to find out the time and circumstances to which the Spirit
  of Christ in them was pointing when he predicted the sufferings of the
  Messiah and the glories that would follow. 12 It was revealed to them
  that they were not serving themselves but you, when they spoke of the
  things that have now been told you by those who have preached the
  gospel to you by the Holy Spirit sent from heaven. Even angels long to
  look into these things.  1 Peter 1:10-12 NIV


Many passages in the Old Testament were considered to be Messianic well before the time of Christ. One theory was that there would actual be two Messiahs.  This arose out of an attempt to reconcile what appeared to be both a suffering Messiah and a conquering Messiah.  These were known as Messiah Ben Joseph (or Ephraim) and Messiah Ben David.  

The Messiah Ben Joseph (son of Joseph) indicated the sufferings that Joseph, the son of Jacob, endured at the hands of his brothers and during the first part of his time in Egypt.  Interestingly enough, Joseph became as Pharaoh in Egypt, much like Jesus, who did suffer at the hands of His brothers and the forces of another country, but who now reigns as King of Kings.  

Messiah Ben David would be a king.

So, Isaiah, like Peter reveals, likely searched intently and with the greatest care trying to find out the time and circumstances when Messiah would come.  He likely did not understand everything about it, but more than likely understand a good bit.