1 Corinthians 2:11

For what man knoweth the things of a man, save the spirit of man which is in him? even so the things of God knoweth no man, but the Spirit of God (KJV)

Then: Paul plops down two basics about the Holy Spirit. First he is omniscient and second he is a communicator. Paul deposits these thoughts in the Corinthians' minds for them to know and use. Henry describes what's happening between man to Spirit to God and God to Spirit to man. The connection is so close (Triune God) that God and the Spirit are united, one and the same. Paul is showing the proof of the divinity of the Holy Spirit.

Now: We don't spend a lot of time wondering about the place of the Holy Spirit in the trinity. As we come to know Christ, it's embedded in our learnings and conversations with the Lord. Paul's teachings have already clarified it for us. Confrontation sometimes occurs with those who argue a monotheistic (one) God cannot be three. They do not separate the various functions of the Lord and cannont understand "God in three persons." I personally compare it to my personal status as daughter, spouse, and parent. One person, doing three things. Or I compare it to the three dimensions of any physical object - height, width, and depth. One object, three sides. God is one. Paul's explanation helps our understanding of who God is.

Extra Source: Commentary on the Whole Bible Acts to Revelation Vol VI by Matthew Henry online at http://www.ccel.org/ccel/henry/mhc6.iCor.iii.html