I slept, and dreamed that life was Beauty;
I woke, and found that life was Duty.
Was thy dream then a shadowy lie?
Toil on, poor heart, unceasingly;
And thou shalt find thy dream to be
A truth and noonday light to thee.

Life a Duty, reported in Bartlett's Familiar Quotations, 10th ed. (1919). Compare: "Straight is the line of Duty, / Curved is the line of Beauty, / Follow the straight line, thou hall see / The curved line ever follow thee", William Maccall (c. 1830).