This text comes from The Book of Scottish Song, edited by Alexander Whitelaw, a historical songbook transcribed on Wikisource and reproduced from the pinned revision linked below.
O say not—"Love will never
Breathe in that breast again;"
That "where he bled, must ever
All pleasureless remain."
Shall tempest-riven blossom,
When fair leaves fall away,
In coldness close its bosom
'Gainst beams of milder day
O never!—nay
It blooms—whene'er it may.
Though ruthless tempest tear—
Though biting frosts subdue—
And leave no tendril where
Love's pretty flowrets grew;
The soil, all ravag'd so,
Will nurture more and more,
And stately roses blow
Where gowans droop'd before.
Then why—O! why
Should sweet love ever die?