What is the meaning of the verb せり

[Sivan]

Hi,
I'm wondering about the meaning of せり in this Tawara Machi poem:

栗三つ茹でて一人の秋とせり遠くに君の海感じつつ

I think it might be coming from classical Japanese but I'm not sure, would appreciate any info about it and links to further explanations if you have any, thank you!

 

[Toritoribe]

Yes, it's 未然形 of す (= する) + 終止形 of り for the perfect tense, i.e., equivalent to した in modern Japanese. Here's a list of classical auxiliary verbs. (Although classical Japanese, especially some specific classical auxiliary verbs are sometimes hard to interpret even for native speakers, I believe 俵万智 didn't use complicated ones in her poems.)

助動詞一覧表（活用表）・古文 - 学ぶ・教える．COM
(all in Japanese)