秋の鹿は笛に寄る
(Aki no shika wa fue ni yoru; “An autumn deer approaches a whistle”)

Definition:

Destroying oneself for the sake of love. Alternately, being in danger or being used by others after having one’s weakness taken advantage of. From the practice of hunters, when the deer mating season rolls around in the fall, of using whistles that resemble the calls of female deer to lure in and capture the males.

Breakdown:

We begin with a topic, marked by the particle は (wa); the topic in question is the noun phrase comprising primary noun 鹿 (shika), “deer,” and modifying noun 秋 (aki), “autumn,” connected by the associative particle の (no). This topic acts like a grammatical subject, and the verb it enacts is 寄る (yoru), “to approach, in sentence-final form. The particle に (ni) shows that this action is in the direction of the noun 笛 (fue), “whistle.”

Notes:

Although the nuance is different, this phrase is often paired with 飛んで火に入る夏の虫 as another example of self-destructive behavior.

An alternate version of the saying replaces 秋の with 妻恋う (tsuma kou), literally “wife-loving”; also it seems that the verb phrase was originally 心を乱す (kokoro wo midasu), “to throw one’s heart into disarray.”

Both this saying and that of the summer insects come to us from a passage in the revenge epic 曾我物語 (Soga monogatari).

Example sentence:

「あのおじいさんは若い頃、愛してた女の人に騙されたらしいよ。それからずっと、秋の鹿は笛に寄るからと言い張り、独身の生活を送ってきたの。なんともいえない人生だよね」

(“Ano ojiisan wa wakai koro, ai shiteta onna no hito ni damasareta rashii yo. Sore kara zutto, aki no shika wa fue ni yoru kara to iihari, dokushin no seikatsu wo okutte kita no. Nan to mo ienai jinsei da yo ne.”)

[“They say that when that old man was young, he was led on by a woman he loved. And ever since, he’s always said that ‘love will lead you astray’ and stayed single. What a life that must have been.”]