This text comes from The Poetical Works of Robert Burns, a historical songbook transcribed on Wikisource and reproduced from the pinned revision linked below.
Let not woman e'er complain
Of inconstancy in love;
Let not woman e'er complain,
Fickle man is apt to rove:
Look abroad through Nature's range,
Nature's mighty law is change;
Ladies, would it not be strange,
Man should then a monster prove?
Mark the winds, and mark the skies;
Ocean's ebb, and ocean's flow:
Sun and moon but set to rise,
Round and round the seasons go.
Why then ask of silly man,
To oppose great Nature's plan?
We'll be constant while we can—
You can be no more, you know.