Each stanza in "Auspex" shows the different stages of a natural process.
In "My Last Duchess" by Robert Browning, the situation which brings the duke and the agent together is the duke's intention to remarry.
His wife died (or was killed, we will never know for sure), and he lost a lot of money, which is why he needs to marry into a rich family so as to regain what he lost. This is the reason why he met with the agent, so as to marry his cousin or something.
