Tariki Sensei
One of the interesting things about pre-genbun itchi Japanese diglossia is that although in theory the written language had been faithfully preserved for centuries, in practice it was more often used as a simple encoding for the contemporary spoken language. One area where this is often becomes apparent is in the mass of past and/or perfective verb endings.
That particular part of Japanese reached its peak of complexity during Early Middle Japanese; it's been a downhill slope of simplification ever since, and today we're basically down to the -ta ending. But because Early Middle Japanese also served as the model for Classical Japanese, as the centuries rolled on the literary community were expected to master and preserve fine distinctions of a sort that their native language clear-felled and paved over increasingly far back in the mists of history.
[Update: Leonardo Boiko has done the hard work of listing up all these suffixes with their traditional analyses along with Frellesvig's views, for those who want more context.]
In Kanbun kundoku to kindai Nihongo no keisei 漢文訓読と近代日本語の形成 ("Kanbun kundoku and the formation of [Late] Modern Japanese") (Bensei Shuppan, 2011), Saitō Fumitoshi 齋藤文俊 quotes a marvelous rant on this topic by Ochiai Naofumi 落合直文, from an essay published in 1890 called "Shōrai no kokugo" 将来の国語 ("The national language/Japanese of the future"). After listing the various past/perfective verb endings (ki, tsu, etc.), Ochiai says [warning, casual translation]:
Each of these various endings must be used at different times. Sometimes the normal past [普通の過去] is required, sometimes the imperfect [半過去], sometimes the natural past [自然の過去], sometimes the caused past [使然の過去], sometimes the exclamatory past [驚嘆の過去], and sometimes the settled past [治定の過去]. To go further, each has its meaning, and these should not be confused. Yet is it not the case that people today are indifferent to these distinctions, so that the keri partisans [けり党] use only keri, the nu faction [ぬ派] use only nu, the tsu league [つ団] use only tsu, the tari union use only tari, and the ki group use only ki? [...] Even in an age of economism like today, this is really too much.
Among my friends is a man known as "Tariki Sensei." He got this name because whenever he speaks of the past he uses tariki. Another of my friends is indifferent to verb endings. He once showed me something he had written in which he first used ki, then followed this with nu, threw in a tari, a tsu, a keri, and who knows what else. This struck me as uncharacteristic given his customary indifference, and when I read more closely, strange to say, it turned out that he was simply using whichever ending he pleased, no matter the intended meaning. When I asked him about it, he replied that the variation was intentional, to avoid making the text dull by repeating the same word too many times.
(Part of Saitō's project is to explore the different verb endings preferred for essentially the same meaning in kanbun-influenced and "pure" Japanese texts — for example, keri is almost never used in the former. Thus, the rules included not only semantic distinctions but also arbitrary stylistic requirements.)
leoboiko:
Question: in "whenever he speaks of the past", do we actually mean _speaks_ (as in spoken conversation)? I mean, have some affected intellectuals deliberately chosen to use this suffix or that, ending up with verbal quirks not unlike the "yakuwarigo" of manga characters? Because if so, that's just delightful!
It feels like every author I read on the "past" suffixes ascribe slightly different nuances to them (and of course any counterexample is just decadence from the "original" meaning…) Ochiai's Another Friend's stylistics-based grammar model feels so much more predictive.
I seem to have lost my notes on Fujii Sadakazu's "Kobun no Yomikata", but if I recall correctly, he denies the traditional 詠嘆 (eitan, "exclamation, admiration") nuance of "keri", saying instead that its original use is as a marker of "transmitted knowledge" (伝来) – the past as handed from the ancients (or, in poetry, making it sound as such) – and that any admiration is a consequence of social attitudes toward this particular kind of past.
From a linguistics point of view, I'm not sure how seriously should we take his proposals; but looking in the web for Fujii stuff, it seems he even has a phono-semantic classification of the past-related suffixes, with a cool-looking tetrahedron: https://www.iwanami.co.jp/hensyu/sin/sin_kkn/kkn1012/sin_k563.html