William Juniper, A Merry, Ingenious, and Diverting Work Entitled Liber Compotorum Felicium: Or, The True Drunkard's Delight
(London: The Unicorn Press Ltd, 1933), p. 327 (with my emendation of spirit-flattering to spirit-flattening):
And the result? Well, for one thing, the gentlemen (and ladies) of England are steadily losing their figures and falling victim to fatty degeneration, shortness of breath, oiliness of complexion, thickness of utterance and deplorable embonpoint. And not only are they losing their figures, but they are also losing their heads, for cocoa is a dull, soul-clogging, spirit-flattening, stupefying drink, provocative of apathy, drabness and smugness, political stodginess and obliqueness, and sullen rebellion and disloyalty.
See also these lines from G.K. Chesterton's "The Song of Right and Wrong":
Cocoa is a cad and coward,
Cocoa is a vulgar beast,
Cocoa is a dull, disloyal,
Lying, crawling cad and clown,
And may very well be grateful
To the fool that takes him down.