The people of Israel faced difficulties, not unlike many of the difficulties we face in our lives.
Three truths about God are given to encourage the people. These truths are God's encouragement to us at times like this, also.
Verses 6(b) - 8(a) tell us that we all live temporal lives here.
Verses 15-16 tell us how limited we are, compared to God.
The first verse tells us of our humanity in pointing to our sin, and as God as the one able to address our need. (elsewhere Isaiah tells us our sins separate us from God).
The last verse speaks also of our growing weak and weary.
When we face death--our own or anothers, we come face to face with our own finiteness. Then, he contrasts us with God.
Verses 12-14 His infinite wisdom and knowledge.
Verses 21-22 He is in control watching over His creation.
Verses 23-24 He controls history.
Verses 25-26 He is sustaining and keeping His creation.
If He's in control, Why does it sometimes seem otherwise?
We experience trials and troubles, we face sickness and death, we seemingly face unanswered prayers.
God comforts Israel by answering these same questions.
Verse 11 He cares for us as a shepherd.
Verse 27 We should never feel as if He's forgotten us.
Verse 28 He never grows weary.
Verses 29-30 He meets our needs as we "wait" upon Him.