The sensus plenior

Remember the post from two days ago on John 19?  I mentioned that it referenced Psalm 22 and the casting of lots for Jesus' clothing, although Psalm 22 didn't really seem to prophesy about that event.  Well, I was reading today in "How to Read the Bible for All Its Worth" that New Testament authors, since they were inspired by the Holy Spirit to write what they did, were allowed to read into the Old Testament and use it as allegory for New Testament events (most relating to Christ).  This secondary meaning is called the sensus plenior or the "fuller meaning" of the OT text.  Modern day readers of the bible should not try to make up their own sensus plenior, however, because we are not inspired by the Holy Spirit to do this.  We are illumined readers of the text, not inspired authors.  So when we read the OT and only see it in its original context, that's fine.  The NT writers can use those older texts to help us understand the new covenant in a better way, but we should avoid doing this on our own.