St. Martin's Summer Poem by Robert Louis Stevenson

AS swallows turning backward
When half-way o'er the sea,
At one word's trumpet summons
They came again to me -
The hopes I had forgotten
Came back again to me.

I know not which to credit,
O lady of my heart!
Your eyes that bade me linger,
Your words that bade us part -
I know not which to credit,
My reason or my heart.

But be my hopes rewarded,
Or be they but in vain,
I have dreamed a golden vision,
I have gathered in the grain -
I have dreamed a golden vision,
I have not lived in vain.