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.
Oh! not when hopes are brightest.
Is all love's sweet enchantment known;
Oh! not when hearts are lightest.
Is all fond woman's fervour shown:
But when life's clouds o'ertake us,
And the cold world is clothed in gloom
When summer friends forsake us,
The rose of love is best in bloom.
Love is no wandering vapour,
That lures astray with treacherous spark;
Love is no transient taper,
That lives an hour and leaves us dark:
But, like the lamp that lightens
The Greenland hut beneath the snow,
The bosom's home it brightens,
When all beside is chill below.