Actually the earliest reference was found in some of the medieval writings of the famous scholar St. Grogginus, often known as the arse-faced monk (for reasons best not discussed here). It is believed that St. Grogginus was one of the first of the scholastics to shift away from the Aristotelian-infleunced/neo-Platonic Christian metaphysic in favour of brewing heavily hopped West Coast IPAs. Although the translations are contentious, the academically accepted translation of Reflections of a God Fearing Man upon the brewing of a Shit-Hot IPA by the Grace of the Almighty (circa 1472) by Booby & Bumspittle is rendered thus:
"...and lo upon reflection, it seemeth to me - as lazy a man as God hath ever created - that I could be rid of this horrid pale blue 70 litre icebox which doth plague me with it's presence and causeth much grief to me without an adjustable twin roller mill and simply use my night-dress as a primitive filter to containeth my grains..." (pg. 156)
and later in the same volume:
"...woe to he without the pleasing sound of the gulls to soothe his mash bed, and rejoice verily for he that doth dunk his cereals wrapt (sic) herein the garments that once girded his loins...for even though thine losses to trub be mighty, thine step mashing with an adequate paddle blessed by the Father be a job done in an angels fart (translators note - this last saying was a common one at the time and through a mistake in translation by the original Professor Dontwantnuthinbutagoodtimehowcaniresist was eventually rendered as 'in the blink of an eye')..." (pg. 212).
It is worth bearing in mind that although 3v was well entrenched at the time, the invention of HERMS by the Spanish sailor and inventor Jose Wheresamyshipgone was still months away (and of course that famous tale involving the clydesdale, three sheep bladders and a local three legged goat named Pepe need not be recounted here haha!).
Back on topic.
St. Grogginus famously created recipes with measurements that called for "enough hops so that the aroma shall be experienced even by those in the holy land" (Man is Nought but Hops in the Whirlpool of God circa 1478) and was once quoted as saying "surely if Christ himself did strike me in the throat with his notably skilled Shaolin-trained Iron Palm, this be the level of bitterness that a good brew should contain" (Liars and Paederasts: Famous Medieval Scholastic Drunkards, Glammetalwasfun & Whathappennedtoblackielawless, 1984, pg xi).
But of course the above replies are more credible in terms of recent innovations. The original biab threads are a hoot to read. And if you think this post was long, wait until you read PP's!