How would you find the theme of this poem?

Question

anonymous · Answer

Natural Progress
In all faith, we did our part:
generated punctually, prepared adequately,
ejected promptly,
and swam in the approved manner
in the appropriate direction;
did all instinctive things well,
even eagerly—
an exemplary start.

But then the barrier: unexpectedness
unexpectedly.
(They did not tell us this).
To go back impossible, unnatural:
so round; many times;
we tired ourselves.
Where were the promised homes,
embedded in the soft wall?
Or the anticipated achievement
so momentous, fulfilling?

So we died:
what else was there to do?
But in all faith, we did our part!