One of the things I've been occupying my zombie moments with is going through back issues of Notes and Queries in the hopes of finding items of interest ... I just came across this set of queries and notes (from the texts at Project Gutenberg):

Notes & Queries 1849.12.22

_Coffee, the Lacedaemonion Black Broth._ Your "notes on Coffee" in No. 2. reminded me that I had read in some modern author a happy conjecture that "coffee" was the principal ingredient of the celebrated "Lacedaemonian black broth," but as I did not "make a note of it" at the time, and cannot recollect the writer from whom I derived this very probable idea, I may perhaps be allowed to "make a query" of his name and work. R.O.

Notes & Queries, No. 9, Saturday, December 29, 1849

_Coffee, the Lacedaemonian Black Broth._--Your correspondent "R.O." inquires what modern author suggests the probability of coffee being the black broth of the Lacedaemonians? The suggestion, I think, originated with George Sandys, the translator of Ovid's _Metamorphoses_. Sandys travelled in the Turkish empire in 1610. He first published his _Notes_ in 1615. The following is from the 6th edit. 1652, p. 52.:-- "Although they be destitute of taverns, yet have they their coffa-houses, which something resemble them. Their sit they, chatting most of the day, and sip of a drink called coffa (of the berry that it is made of), in little _China_ dishes, as hot as they can suffer it; black as soot, and tasting not much unlike it (why not that black broth which was in use among the Lacedaemonians?) which helpeth, as they say, digestion, and procureth alacrity," &c. Burton also (_Anatomy of Melancholy_) describes it as "like that black drink which was in use among the Lacedaemonians, and perhaps the same." E.B. PRICE.

Notes & Queries 1850.01.26

_Lacedaemonian Black Broth_.--Your correspondent "W." in No. 11., is amusing as well as instructive; but it does not yet appear that we must reject the notion of coffee as an ingredient of the Lacedaemonian black broth upon the score of _colour_ or _taste_. That it _was_ an ingredient has only as yet been mooted as a _probability_. Pollux, to whom your correspondent refers us, says that [Greek: zomos melas] was a Lacedaemonian food; and that it was called [Greek: aimatia], translated in Scott and Liddell's _Lexicon_, "_blood-broth_." These lexicographers add, "The Spartan black broth was made with blood," and refer to Manso's _Sparta_, a German work, which I have not the advantage of consulting. Gesner, in his _Thesaurus_, upon the word "jus," quotes the known passage of Cicero, _Tusc. Disp_. v. 34., and thinks the "jus nigrum" was probably the [Greek: aimatia], and made with an admixture of blood, as the "botuli," the _black_ puddings of modern time, were. Coffee would not be of much lighter colour than blood. A decoction of senna, though of a red-brown, is sometimes administered in medicine under the common name of a "_black_ dose." As regards the _colour_, then, whether blood or coffee were the ingredient, the mess would be sufficiently dark to be called "_black_." In respect of _taste_, it is well known, from the story told by Cicero in the passage above referred to, that the Lacedaemonian black broth was _disagreeable_, at least to Dionysius, and the Lacedaemonians, who observed to him that he wanted that best of sauces, hunger, convey a confession that their broth was not easily relished. The same story is told with a little variation by Stobaeus, _Serm_. xxix., and Plutarch, _Institut. Lacon_., 2. The latter writer says, that the Syracusan, having tasted the Spartan broth, "spat it out in disgust," [Greek: dyscheranunta apoptusai]. It would not have been unlike the Lacedaemonians purposely to have established a disagreeable viand in their system of public feeding. Men that used iron money to prevent the accumulation of wealth, and, as youths, had volunteered to be scourged, scratched, beat about, and kicked about, to inure them to pain, were just the persons to affect a nauseous food to discipline the appetite.

This was appended to the foregoing:

R.O. _Lacedaemonian Black Broth_.--I should be glad to know in what passages of ancient authors the Lacedaemonian black broth is mentioned, and whether it is alluded to in such terms as to indicate the nature of the food. It has occurred to me that it is much more probable that it was the same _black broth_ which is now cooked in Greece, where I have eaten of it and found it very good, although it looked as if a bottle of ink had been poured into the mess. The dish is composed of small cuttle-fish (with their ink-bags) boiled with rice or other vegetables.

So ... as we've long suspected ... the Spartan way of life was fuelled by coffee! Probably not, of course, but now we can watch the myth promulgate on the web ...