With a lantern that wouldn't burn
In too frail a buggy we drove
Behind too heavy a horse
Through a pitch-dark limitless grove.
And a man came out of the trees
And took our horse by the head
And reaching back to his ribs
Deliberately stabbed him dead.
The ponderous beast went down
With a crack of a broken shaft.
And the night drew through the trees
In one long invidious draft.

The most unquestioning pair
That ever accepted fate
And the least disposed to ascribe
Any more than we had to to hate,
We assumed that the man himself
As they have got older, their own weapons against darkness have been gradually fading to “a lantern that wouldn’t burn” and the buggy has become “too frail”. Likewise, the horse is described as a “too heavy” draft horse because it is good for no other purpose and cannot help them to escape from any emergency that may arise; indeed, it is an easy victim when a life-changing event occurs. 
 The death that is portrayed is therefore that of comfort and security, which can come suddenly to anyone and leave them with no option other than to rely entirely on their own ability to “walk the rest of the way”. The symbol works just as well for a breakdown in health or a loss of fortune, social standing, or the means to earn a living. Any disaster can arrive without warning and leave one’s “buggy” without the means to draw it forward. The man who kills the horse is Fate, intervening without warning to leave one exposed to the “long invidious draft” represented by the dark wood through which the couple are travelling. 
 It should be noted that the couple accept what has happened as being normal and natural and not to be fought against or even objected to. They are: “The most unquestioning pair / That ever accepted fate”, and would appear to take a very different line to that of, say, Dylan Thomas who would have urged them to “rage against the dying of the light”. Frost was himself an old man when he wrote this poem (it appeared in his final collection “In the Clearing”, published in 1962 when Frost would have been 87 or 88 and had less than a year left to live).
The Draft Horse