The auxiliary verb （助動詞） ～けり is added to the ren’youkei of verbs and the 「かり」ren’youkei of adjectives. ～けり is derived from 来あり （きあり）and this is where a great deal of its meaning comes from. Much like the modern ～て来る form, it refers to something in the past that continues – “comes”- to the present.
It has three uses.
- 継続 Continuative Aspect
This is the most basic usage. It denotes that the verb has continued from the past into the present. Possible modern translations include ～ている, ～てある, and ～てくる・～てきた. Recall that ～ている form only denotes a present perfective aspect when the base verb is a continuous verb (ie. 知っている [I exist having known] vs. 食べている [I am eating]). ～けり, however, is able to give all verbs this present perfective nuance. Translate into modern Japanese accordingly.
紅葉神代より秋は散りけり。（紅葉は神代から秋に散って来た。）(Maple leaves have come to fall in the autumn since the age of the gods.)
- 伝聞 Renarrative Mood
This use is commonly an over simplified use of ～けり. However, its treatment as a simple past tense obscures its true meaning. Here, it does denote that something occured in the past, but the nuance is that the speaker did not directly experience or observe the event, or that the event is displaced from the present and the speaker is reminiscing. For this reason, it is often used to speak about events in the remote past. Modern include ～たそうだ, ～たという, ～たとされている, and たなぁ.
Ex) 京へ帰りけり。 （京へ帰ったという・京へ帰ったそうだ）(It is said that he returned to the capital.)
- 詠嘆 Poetic Emphatic Mood
When used in classical poetry, as well as prose for effect, ～けり is very often used for poetic emphasis. It has a nuance of noticing something special about something that has obviously existed for some time. Modern translations are wordy, but are something like [Xに初めて気がついて]、Yのだなぁ / Yということが素敵に思う / Yなぁ.
Ex) 犬なども心あるものなりけり。（犬にも心があるものなのだな。）(Wow, even a dog has a soul.)
As a 助動詞, ～けり has a conjugation. It conjugates as a defective ラ行変格活用動詞; the mizenkei is rarely used, and the ren’youkei and meireikei are lacking.
Classical Japanese 