Alec Motyer, The Prophecy of Isaiah, (on Isaiah 9:1):
As always the people of God must decide what reading of their experiences they will live by. Are they to look at the darkness, the hopelessness, the dreams shattered and conclude that God has forgotten them? Or are they to recall his past mercies, to remember his present promises and to make great affirmations of faith? Isaiah insists here that hope is a present reality, part of the constitution of the ‘now’. The darkness is true but it is not the whole truth and certainly not the fundamental truth.