It's from the very old English poem:
Roundabouts and swings by Patrick R Chalmers
It was early last September nigh to Framlin'am-on-Sea,
An' 'twas Fair-day come to-morrow, an' the time was after tea,
An' I met a painted caravan adown a dusty lane,
A Pharaoh with his waggons comin' jolt an' creak an' strain;
A cheery cove an' sunburnt, bold o' eye and wrinkled up,
An' beside him on the splashboard sat a brindled tarrier pup,
An' a lurcher wise as Solomon an' lean as fiddle-strings
Was joggin' in the dust along 'is roundabouts and swings.
"Goo'-day," said 'e; "Goo'-day," said I; "an' 'ow d'you find things go,
An' what's the chance o' millions when you runs a travellin' show?"
"I find," said 'e, "things very much as 'ow I've always found,
For mostly they goes up and down or else goes round and round."
Said 'e, "The job's the very spit o' what it always were,
It's bread and bacon mostly when the dog don't catch a 'are;
But lookin' at it broad, an' while it ain't no merchant king's,
What's lost upon the roundabouts we pulls up on the swings!"
"Goo' luck," said 'e; "Goo' luck," said I; "you've put it past a doubt;
An' keep that lurcher on the road, the gamekeepers is out."
'E thumped upon the footboard an' 'e lumbered on again
To meet a gold-dust sunset down the owl-light in the lane;
An' the moon she climbed the 'azels, while a night-jar seemed to spin
That Pharaoh's wisdom o'er again, 'is sooth of lose-and-win;
For "up an' down an' round," said 'e, "goes all appointed things,
An' losses on the roundabouts means profits on the swings!"