We must first set this verse in its context. Paul has given in chapters 5, 6 and 7 of the Epistle to the Romans three definitions of that life which, according to 1.17, is promised for the man who is righteous by faith. In chapter 8 he goes on to define it further and finally as life in the Spirit, that is, life in obedience to God's law established in its true character by God's gift to us of His Spirit. The basic statement of this definition is contained in verses 1–11. In verses 12–16 the meaning of obedience is clarified. Its substance is summed up in verse 15. Obedience to God's law is to call God ‘Father’ in all seriousness and sincerity, in gratitude and joy. This, as Barth has pointed out, is in principle the whole of our obedience; for it naturally involves seeking wholeheartedly to please Him in thought, word and deed, and to avoid displeasing Him. Verse 17 by its movement of thought from sonship to heirship effects the transition to the subject of Christian hope, with which verses 17–27 are concerned. Life in the Spirit, life under God's law as established by His Spirit, life in obedience to God, is life characterised by hope. The content of the hope is indicated by verses 18, 19 and 21, its present painful context by verse 20.