"Our sweetest songs are those which tell of saddest thought"?
It is the work of Laurence Binyon, and published in his London Visions.
Now these are merely my opinions, and should not be adopted by you: nor need they ever become yours, unless your progress towards the distant goal of a perfect appreciation of excellence should happen to lead you over the very same spot where I now stand.
Each one of you is a traveller over these delectable mountains, and not what has delighted me or any other pilgrim brings you on your way and holds off fatigue and depression, but what delights you. Only be occupied and ever anew eager in arranging what you admire by order of merit. Examine your preferences, do not rest content with enjoying them, and you will grow aware of niceties and differences in what is admirable that otherwise would have escaped your notice. You will invigorate and render rational what may have seemed the truly mystical fascination which verse exerted over you.
Let me warn you against negative standards. Never record your impressions by enumerating faults, as the newspaper critic so often does. Never accept the absence of apparent flaws as proof of the presence of excellence. Keep to the positive merits and try to define them; merely turn away from what calls for blame. Disparaging warps the mind far worse than over-lauding. Above all, institute comparisons whenever you find two poets treating the same theme or using the same form with felicity to diverse effect, or in any way rivalling one another. Animals see, breathe and feel, man alone discovers, appreciates and admires; it is not enough to passively enjoy; we must create order in our experiences.
