While follow eyes the steady keel, the vessel grim and daring:
But O heart! heart! heart!
O the bleeding drops of red,
Where on the deck my Captain lies,
Fallen cold and dead.
2
O Captain! my Captain! rise up and hear the bells;
Rise up—for you the flag is flung—for you the bugle trills;
For you bouquets and ribbon'd wreaths—for you the shores a-crowding;
For you they call, the swaying mass, their eager faces turning;
Here Captain! dear father!
 This arm beneath your head;
It is some dream that on the deck
You've fallen cold and dead.
3
My Captain does not answer, his lips are pale and still;
Not wanting to believe that Lincoln (the Captain) is dead, the speaker insists that what is happening must be only a dream. Not only the speaker but the whole gathered “mass”–the nation–is in disbelief as to the tragedy they’ve witnessed. 
 The speaker takes the Captain into his arms; by now the Captain has already died. 

O Captain My Captain