Analysis of You Say, Columbus with His Argosies

You say, Columbus with his argosies
Who rash and greedy took the screaming main
And vanished out before the hurricane
Into the sunset after merchandise,
Then under western palms with simple eyes
Trafficked and robbed and triumphed home again:
You say this is the glory of the brain
And human life no other use than this?
I then do answering say to you: The line
Of wizards and of saviours, keeping trust
In that which made them pensive and divine,
Passes before us like a cloud of dust.
What were they? Actors, ill and mad with wine,
And all their language babble and disgust.