Which lines in the poem indicate its theme?
 A Shadow
 by Henry Wadsworth Longfellow
 I said unto myself, if I were dead,
 What would befall these children? What would be
 Their fate, who now are looking up to me
 For help and furtherance? Their lives, I said,
 Would be a volume wherein I have read
 But the first chapters, and no longer see
 To read the rest of their dear history,
 So full of beauty and so full of dread.
 Be comforted; the world is very old,
 And generations pass, as they have passed,
 A troop of shadows moving with the sun;
 Thousands of times has the old tale been told;
 The world belongs to those who come the last,
 They will find hope and strength as we have done.