Even the Spirit of truth; whom the world cannot receive, because it seeth him not, neither knoweth him: but ye know him; for he dwelleth with you, and shall be in you.
John 14:17 (KJV)
The Holy Spirit is the spirit of truth. He makes the truths of the Word of God real to us, He confirms the reality of the Word to our heart. As we live in complete dependence upon the Holy Spirit, He enables us and equips us to do what we cannot do in our own strength.