E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Soft soap, soft solder (pron. saw-der), wiping down with winning words. Punch expressively calls it the milk of human kindness churned into butter. (Anglo-Saxon, butere or butyre, Latin, butyrum, Greek, bout&ybreve;ron, i.e. bou-turos, cow-cheese, as distinguished from goat- or ewe-butter.)
Soft words butter no parsnips. Saying Be thou fed, will not feed a hungry man. Mere words will not find salt to our porridge, or butter to our parsnips.
Fine words, says our homely old proverb, butter no parsnips.Lowell.
He looks as if butter would not melt in his mouth. He looks like a dolt. He looks quite harmless and expressly made to be played upon. Yet beware, and touch not a cat but a glove.
She smiles and languishes, youd think that butter would not melt in her mouth.Thackeray: Pendennis, lx.
He knows on which side his bread is buttered. He knows his own interest. Scit uti foro.
He that has good store of butter may lay it thick on his bread. Cui multum est pipris, etiam oleribus immiscet.
To butter ones bread on both sides. To be wastefully extravagant and luxurious.