Question

What structure does the poet employ in the first stanza of "The Second Coming"?

Answer 1

The first stanza is a reminiscent stanza, it represents a forthcoming of events  

Answer 2

The second stanza has fourteen lines.The structure of the second stanza , then is that of a sonnet.There are some differences with the classical sonnet which have to be taken into account.For instance, the fact that the  sentences in the stanza do not rhyme.It has a iambic pentameter meter, roughly speaking.