This isn't actually a poem but a song. It is all about Burn's beloved Scotland or Caledonia as he refers to it.
There was once a day, but old Time wasythen young,
That brave Caledonia, the chief of her line,
From some of your northern deities sprung,
(Who knows not that brave Caledonia's divine?)
From Tweed to the Orcades was her domain,
To hunt, or to pasture, or do what she would:
Her heav'nly relations there fixed her reign,
And pledg'd her their godheads to warrant it good.
A lambkin in peace, but a lion in war,
The pride of her kindred, the heroine grew:
Her grandsire, old Odin, triumphantly swore, -
"Whoe'er shall provoke thee, th' encounter shall rue!"
With tillage or pasture at times she would sport,
To feed her fair flocks by her green rustling corn;
But chiefly the woods were her fav'rite resort,
Her darling amusement, the hounds and the horn.
Long quiet she reigned; till thitherward steers
A flight of bold eagles from Adria's strand:
Repeated, successive, for many long years,
They darken'd the air, and they plunder'd the land:
Their pounces were murder, and terror their cry,
They'd conquer'd and ruin'd a world beside;
She took to her hills, and her arrows let fly,
The daring invaders they fled or they died.
The Cameleon-Savage disturb'd her repose,
With tumult, disquiet, rebellion, and strife;
Provok'd beyond bearing, at last she arose,
And robb'd him at once of his hopes and his life:
The Anglian lion, the terror of France,
Oft prowling, ensanguin'd the Tweed's silver flood;
But, taught by the bright Caledonian lance,
He learned to fear in his own native wood.
The fell Harpy-raven took wing from the north,
The scourge of the seas, and the dread of the shore;
The wild Scandinavian boar issued forth
To wanton in carnage and wallow in gore:
O'er countries and kingdoms their fury prevail'd,
No arts could appease them, no arms could repel;
But brave Caledonia in vain they assail'd,
As Largs well can witness, and Loncartie tell.
Thus bold, independent, unconquer'd, and free,
Her bright course of glory for ever shall run:
For brave Caledonia immortal must be;
I'll prove it from Euclid as clear as the sun:
Rectangle-triangle, the figure we'll chuse:
The upright is Chance, and old Time is the base;
But brave Caledonia's the hypothenuse;
Then, ergo, she'll match them, and match them always.