The Law dealt with us as slaves - Grace and truth now deal with us as sons. Grace and truth is the new reality; it is the new way that God speaks and it is the new way that He deals with us.  It is the new way that He empowers. Gal 4:4  But when the fullness of the time had come, God sent forth His Son, born of a woman, born under the law,  to redeem those who were under the law, that we might receive the adoption as sons. Gal 4:6  And because you are sons, God has sent forth the Spirit of His Son into your hearts, crying out, "Abba, Father!"  Therefore you are no longer a slave but a son, and if a son, then an heir of God through Christ. In Ephesians, everything begins and ends with Grace. This is the big idea of the New Testament. By grace, we are blessed with every blessing. By graces, we are chosen in Him. By grace, we are redeemed. By grace, we received wisdom and prudence. By grace, His inheritance is in the saints. Grace raises up and places us in heavenly places. We are saved by grace. Grace is the unmerited favour of God. And Grace is the unmerited ability of God. Grace is the unmerited revelation and word of God to us. Grace means the freely given favour and empowering life and voice of God. All three! If there is favour but no voice how does uncommunicated favour help us? If there is only favour but no power toward us, we would be blessed but helpless. We know He is the truth.  There is no truth if there is no Grace and Christ is grace. The juxtaposition here in John 1, is not Law with Truth, it is the law with grace and truth. Truth does not equal law.  The law is not a person. It is a portion of the revelation of truth, but not its fullness.   The grace of God encompasses everything that is in Christ. He interprets it. He displays grace and shows forth the truth.  

Friend, Grace is God giving His son Christ to live His life through us. Grace is Christ within us.