Just thought you might like this note to the song from one of my favourite Burns collections among all our books, Allan Cunningham's 'The Works of Robert Burns With his Life" (1834)
Some exquisite notes to the songs and a very enjoyable biography.
Interesting (to me) to note the similarities to the verses Cunningham quotes and other songs, including 'Silver Dagger'
Jim Carroll

An old Nithsdale song seems to have been in the Poet's thoughts when he wrote this exquisite lyric.
Martha Crosbie, a carder and spinner of wool, some-times desiring to be more than commonly acceptable to the children of my father's house, made her way to their hearts by singing, which she did with great feeling, the following ancient strain :—

Who is this under my window ?
Who is this that troubles me ?
O, it is I, love, and none but I, love;
I wish to speak one word with thee.

Go to your mother, and ask her, jewel,
If she'll consent you my bride to be;
And, if she does na, come back an' tell me,
This is the last time I'll visit thee.

"My mother's in her chamber, jewel,
And of lovers' talking will not hear;
Therefore you may go and court another,
And whisper softly in her ear."

The song proceeds to relate how mother and father were adverse to the lover's suit; and that, exasperated by their scorn and the coldness of the maiden, he ran off in despair: on relenting, she finds he is gone, and breaks out in these fine lines—

" O where's he gone that I love best,
And has left me here to sigh and moan;
O I will search the wide world over,
Till my true lover I find again.

" The seas shall dry, and the fishes fly.
And the rocks shall melt down wi' the sun;
The labouring man shall forget his labour,
The blackbird shall not sing but mourn.
If ever I prove false to my love,
Till once I see if he return."