What is the etymology of とある?


ある ‘some’ is an obvious rentaikei of the verb 有り, ‘to exist’, and its
emergence as a pronominal is due to the kanbun influence of Chinese 有 ɦuwX
‘same’ (Zisk, M. (2018). Middle Chinese Loan Translations and Derivations in
Japanese. Japanese/Korean Linguistics, 24. p. 323).

But what is と in the extended form, とある ‘some, certain’?

Martin, S. E. (1987). The Japanese language through time (p. 397). New Haven:
Yale University Press is silent on that. Iwanami Kogo Jiten just claims the
word exists and gives example, no etymology.




First of all, the meaning of 「とある」 with its fine nuances included would be "
** _a tidbit of_** ", " ** _of sorts_** ", etc. I specifically wanted to state
that before anything because by blindly believing the common "bilingual
dictionary" definitions of 「とある」, which are " ** _some_** " and " **
_certain_** ", one could unconsciously seek an etymological explanation that
would seem valid for those dictionary definitions. I think one would be left
in the dark if one did that.

To rephrase the above paragraph myself, the meaning of 「とある」 is closer to
「ちょっとした」 than it is to 「ある」 in Modern Japanese. The answer to your question,
however, is all in Classical Japanese.

Here is what I learned in high school Classical Japanese a few years ago. FYI,
I took no CJ in college, so you might want to wait for an answer by one of the
experts here.

「とある」＝「と」 + 「ある」

「と」 is an adverb in Classical Japanese. [Weblio
古語辞典](https://kobun.weblio.jp/content/%E3%81%A8+) gives the definitions
「そう」、「そのように」 and 「あのように」.

Originally, the adverb 「と」 was generally used in conjunction with another
adverb 「かく」, which means 「こう」、「このように」, etc. Thus, what we are talking about is
the 「こそあど」 here. Words/phrases such as 「とかく」「とにかく」、「とにもかくにも」, etc. should be
popping up in your head now.

"This and that", "like this and like that", etc. I stated 「とある」 actually meant
" ** _a tidbit of_** ", " ** _of sorts_** " at the beginning, didn't I?

In the 連体詞{れんたいし} (pre-noun adjectival) 「とある」, 「かく」 is not used but is surely
implied IMHO.

" **Existing this way or that way if not in a major enough way so it can be
named** " That would be my personal definition of 「とある」.

