Question

" in vain it mattered not a pin" what does this phrase mean?

Answer 1

A Tragic Story --- William M. Thackeray There lived a sage in days of yore, And he a handsome pigtail wore But wondered much, and sorrowed more, Because it hung behind him. He mused upon this curious case, And swore he'd change the pigtail's place, And have it hanging at his face, Not dangling there behind him. Says he, Ah, the mystery I've found-- I'll turn me round, --he turned him round But still it hung behind him. Then round and round, and out and in, All day the puzzled sage did spin In vain--it mattered not a pin-- The pigtail hung behind him. And right, and left, and round about, And up, and down, and in, and out He turned but still the pigtail stout Hung steadily behind him. And though his efforts never slack, And though he twist, and twirl, and tack, Alas Still faithful to his back, The pigtail hangs behind him.

Answer 2

As far as I think, it is from the poem 'The Pigtail' (we did this too!).
It just means that whatever efforts the sage made to change the pigtail's place, did not work; it was all in vain, and couldn't at all, change its place.