We, heroes and poor devils,
the feeble, the braggarts, the unfinished,
and capable of everything impossible
as long as it's not seen or heard
Don Juans, women and men, who come and go
with the fleeting passage of a runner
or of a shy hotel for travellers,
And we with our small vanities, our controlled hunger for climbing
and getting as far as everybody else has gotten because it seems that is the way of the world.
Pick out the lines from the extract, which shows the over amitious nature of the middle-class people.

Explanation

Capable of everything impossible as long as its not seen or heard.