The early part of this poem reminds us that the donkey is an odd animal. The first stanza refers to the the medieval belief that one's personality/destiny was determined by the alignment of celestial bodies at the moment of one's birth. So the donkey was supposedly born at a moment when "the moon was blood" and other strange things were going on in nature. The point is that the donkey is an odd animal. As beasts go, the donkey is definitely outside the mainstream.
The second and third stanzas continue the idea that the donkey is worthy of ridicule: it has a "monstrous head," and "ears like errant wings." It's "the devil's walking parody / on all four-footed things." And Chesterton is right: we don't admire donkeys for their beauty or their intelligence. To this day, to call a person a donkey (or in older terms, an "ass") is quite an insult.But the last stanza shows the donkey's triumph. Of all the beasts on this planet, the Savior chose only one--the donkey--when He rode into Jerusalem on that Palm Sunday long ago, that "far fierce hour and sweet." In that moment, the donkey was given an honor beyond all other beasts in history. And this poem captures that moment beautifully.
The Donkey
When fishes flew and forests walked
And figs grew upon thorn,
Some moment when the moon was blood
Then surely I was born;
With monstrous head and sickening cry
And ears like errant wings,
The devil's walking parody
On all four-footed things.
The tattered outlaw of the earth,
Of ancient crooked will;
Starve, scourge, deride me: I am dumb,
I keep my secret still.
Fools! For I also had my hour;
One far fierce hour and sweet:
There was a shout about my ears,
And palms before my feet.
