We stood by a pond that winter day,
And the sun was white, as though chidden of God,
And a few leaves lay on the starving sod;
– They had fallen from an ash, and were gray.
Your eyes on me were as eyes that rove
Over tedious riddles of years ago;
And some words played between us to and fro
On which lost the more by our love.
The smile on your mouth was the deadest thing
Alive enough to have strength to die;
And a grin of bitterness swept thereby
Like an ominous bird a-wing….
Since then, keen lessons that love deceives,
And wrings with wrong, have shaped to me
Your face, and the God curst sun, and a tree,

 The ancient Romans studied the flight of birds to predict the will of the gods. This was known as augury, and the priest in charge of this practice was an  augur . 
 The construction ‘a-wing’ is archaic and more concise than the modern ‘on the wing’.  It is also a device, [ epenthesis  to enable the line to fit the meter. 
 The stanza is notable for its contradictions; alive and dead; smile and bitterness; a flying bird, usually thought of as positive, here is ‘ominous’. 
 The word, ‘ominous’, is derived from the Latin ‘omen’ or ‘ominosus’. The speaker senses that the woman is conveying or signifying something sinister.  “An ominous bird a-wing”, however, has connotations of death-symbolising birds such as the raven, appropriately as the poem is about the death of the relationship.
Neutral Tones