Author's Intended Meaning?

I was reading a book for my greek tools class last night and the gentleman (Alan Black) was discussing doing good exegesis. One of the things that he was stressing, as all good bible college professors do, was the need to find the Author's Intended Meaning (AIM). I have always struggled with this idea. I struggle because there seems to be a dichotomy between our means of interpretation and our stance on the source of biblical literature. What I mean is this. When we talk about scripture, defend it, etc. we express the idea that these are not man made works but Spirit of God driven, divine masterpieces. Yet when we study them our goal is to find out what "Paul" or "Matthew" meant. We would argue that they are divine in origin and yet study them as though they were any other piece of literature. I guess the question I am struggling with, is if the Spirit of God is big enough to create within the scripture itself nuansces that even the hand that was writing them did not fully grasp. Is it possible that Paul was being carried along by the Spirit and wrote things that amazed him? If so, what would his intended meaning have to do with anything? I hope this makes sense.