This is a very famous poem by Whitman and is set during the Civil War, as references to the "hospital tent" and dead men lying on stretchers make clear. The point or thesis of this poem seems to be related to war and its infinite cruelty. It is important that there are three corpses that the speaker looks at. The first corpse represents old age, the second, youth, and the third, the prime of life. For each of these stages of life, war has shown itself to be a grim and merciless executor, killing all with perfect equanimity. What is most striking about this poem, however, is the way in which this last corpse is compared to Christ:
Young man I think I know you--I think this face is the face of the
Dead and divine and brother of all, and here again he lies.
Such a comparison operates on a number of different levels. The number of corpses reminds us of the two prisoners that were crucified with Christ, and clearly the force of the poem lies in this comparison of the corpse to Christ and the way that he has been killed "again." Although nearly two thousand years have passed since Christ's first death, and in those two thousand years humanity have made incredible advances in terms of science and ethics, humans still show themselves to kill each other savagely and to show how far they remain from achieving the potential and goodness that Christ represented. Humans continue to blindly extinguish the massive potential that is innate in both themselves and each other.