The moment when, after many years
of hard work and a long voyage
you stand in the centre of your room,
house, half-acre, square mile, island, country,
knowing at last how you got there,
There is no introductory preamble. The second person narrator launches the poem as if admonishing the reader. This is a hook to capture the reader’s interest, a device known as  in media res , meaning ‘in the middle of things’. 
 
 The poet is referring to humanity’s striving for constant ‘improvement’ and love of exploration and adventure. 
 Note that the poem begins with a subordinate clause, building tension as the reader proceeds to the main clause at the end of the stanza, a device known as  anastrophe .
The Moment