The phrase the milk in the coconut denotes a puzzling fact or circumstance; the allusion is to the question of how the milk got into the coconut.
The Oxford English Dictionary (3rd edition – 2002) states that this phrase is of American-English origin, because the two earliest occurrences that it has found, which date from 1840 and 1853 respectively, are from U.S. publications.
But, according to the earliest instances that I have found, the milk in the coconut is in fact of British-English origin; the earliest is from a letter to the editor, published in The Morning Chronicle (London) of Saturday 10th November 1832:
Sir—Will you allow me, through the medium of your influential columns, to draw the attention of the Commissioners of Sewers, or some other authoritative body, to the general disgraceful state of the foot-pavements. And while I ask these worthies why things are allowed to remain in such unreformed state, I will, if their eyes be not closed against reason, point out a remedy at once simple and, in my humble opinion, effectual. To the point, Sir—The clause in the Act of Parliament, 11 Geo. III. cap. xxv., dinned in the ears of the public every St. Thomas’s day, enjoins each individual to cause the footway before his house to be swept or scraped by ten o’clock in the morning, the neglect of which incurs, or should incur, the penalty of ten shillings. This penalty, I understand, goes to the King. Ah, ah! here is the mystery unravelled. This accounts for the milk in the cocoa-nut. If it be true that the penalty is thus disposed of, surely none are such fit subjects for informing as the police-officers, and as their instruments of correction are perambulating the streets from the hour of eight in the morning till seven in the evening, and must be feelingly alive to the growth of the evil complained of, they should be instructed to rouse the inhabitants to a sense of their duty, and in the event of disobedience, to summon them according to the Act made and provided. If this be done, I venture to prognosticate a speedy termination of their labours, and a quick discernment by the public of a favourable change.
Your obedient servant,
Nov. 7, 1832. J. M. K.
The metaphor appeared in the (tongue-in-cheek?) review, published in The Morning Post (London) of Monday 11th July 1836, of Observations on the Curiosities of Nature, a collection of miscellaneous papers by William Burt:
In his very amusing paper, “Phenomenon in the Pulse,” the author’s conclusion seems hardly borne out by his premises. The experiment by which the whimsical conclusion, “that the pulse is the regulator of the hours as well as of the minutes, and gives an intimation of them by beating audibly the hours and the minutes, when placed in a proper position, and supplied with the requisites auxiliaries,”— in other words, that the pulse of the thumb answers, or might be made to answer, all the purposes of a watch—is supported, we have been familiar with from our “boyish days.” There can be no doubt that the pulsation of the artery explains the vibration of the string, and its appended auxiliary, the button; but in the correctness of the ulterior inferences, which the author has drawn from this ingenious and inconclusive experiment our faith is not sufficiently robust to enable us to coincide. The author’s account of this “wonderful phenomenon,” or rather of the order in which the different parts of the operation successively take place, is as follows:—
“About three minutes after the thread is taken, and the head steadily fixed, the button will strike the last hour announced by the clock. Five minutes after that it will strike in a feebler manner the number of minutes elapsed since the clock struck: if a quarter past, for instance, it will strike fifteen: when five minutes more have elapsed it will strike twenty; and so increase every five minutes till it has tolled sixty; after which it will very shortly strike in a louder manner the next hour, and proceed as before, telling the minutes every successive five, until it commences a new hour.”
Assuming the truth of the proposition involved in this experiment, the corollories [sic] which are deduced are numerous and interesting. We can then explain “why our day has been divided into twice twelve hours rather than into twenty-four;” “why those hours are again divided into sixty minutes;” “why our reckoning is made to begin at one;” why there is milk in a cocoa nut, and a multitude of other matters equally important.
Likewise, the image was used in the review, published in The Morning Post (London) of Friday 2nd December 1836, of Adventures in the Moon, and other Worlds, by an anonymous author:
The foregoing passage has no very obvious connection with our foreign policy; and yet, by some mysterious affinity, the juvenile elder reminds us of our Foreign Secretary. Our feminine readers may divine the reason; the most vindictive would hardly refuse our elderly Cupid the appropriate consolation of a lunar kaleidoscope—
“Whoever is sufficiently vain has no need of any other advantages.” (Cupid again.)
– Sleeper. “But upon what ground is he vain? He has neither fortune, friends, nor health, and I cannot discover that he has any beauty. Is he a man of genius, or what endowments has he to justify this pretence?
– Spirit. “None at all; but you must have observed that men are not vain by force of reasoning; a man of true authentic vanity wants no argument to support it. And there is no happiness comparable to this; the peace of mind from vanity far excels that from benevolence, from a clear conscience, or from any other such possession.”
This explains the origin of the milk in a cocoa-nut—of the self complacency in a Palmerston—of the Thrasonical* fatuity in a Melbourne— and of sundry other enigmatical and obscene phenomena, which are too obvious to require, and too offensive to endure, a more specific enumeration.
(* The adjective Thrasonical means boastful, vainglorious; it is from Thraso, the name of a braggart soldier in Eunuchus (The Eunuch), a comedy by the Roman playwright Terence (Publius Terentius Afer – circa 190-159 BC); Thraso is from Greek Θράσων (= Thrásōn), from θρασύς (= thrasús), meaning bold, spirited.)
Another early occurrence of the phrase is from The Morning Post (London) of Saturday 8th September 1838:
We do not remember a finer specimen of the genuine non-sequitur than is to be found in the Morning Chronicle of yesterday.
Our philosophical contemporary gives an extract from a speech of my Lord Normanby’s at Roscommon, in which the Noble Lord is made to hint his feeling that “the existing laws are not in every instance in unison with the wishes and circumstances of the people.” It would be very odd if the law were in every instance in unison with the wishes of the people, and especially of such a people as the Irish, who, from whatever cause, are peculiarly exposed to the operation of it. One could not reasonably expect, for instance, that the law that interferes with attacks on life or property should be very popular with the midnight legislators who set fire to a cottage, for the sake of a little ball-practice at the inmates, as they endeavour to escape through the burning roof.
But to remind an Irish audience that the laws are not in unison with their wishes, does not, at first sight, appear the best way of keeping them quiet. The Chronicle, however, thinks—or speaks at least—differently; and therein consists the notability of the non-sequitur. “These are not,” quoth our Ministerial contemporary, “the words of one who seeks to arouse the passions of a people smarting under the recent sense of wrong and insult.”
That this inference is not quite legitimately deducible from the premises, must, we think, be admitted; but if it be not a logical conclusion, it nevertheless affords a very useful hint. To be sure, the hint wants the charm of novelty; for a too well- known Irish mendicant has acted on it for some time past, though not with the happiest effects. Mr. O’Connell has continually told the “seven millions” that the laws are inapplicable to their state and circumstances; and he has failed to produce tranquillity by so telling them. We suppose we must consider his failure as a mere accidental mode, for we have now the weighty authority of the Chronicle, that to make men discontented is not to arouse their passions; and as the Irish are a decently-behaved sort of persons when their passions are not aroused, it seems clear, from the converse of the proposition, that to make them disaffected is the sure way to keep them quiet.
A valuable light is thus thrown on the hitherto mysterious anomaly in the condition of Ireland. The Conservatives have not only endeavoured to make the Irish satisfied with the existing laws, but they have even passed laws for no other purpose that we can see, except to satisfy them. Does this not fully account for the milk in the cocoa-nut? The Irish are still a discontented people.
The political world ought really to feel deeply indebted to the joint labours of Lord Normanby and the Morning Chronicle.