士道は頬に汗をひとすじ垂らした。

[zuotengdazuo]

士道は頬に汗をひとすじ垂らした。

Hi. The above is the original sentence.
What is the difference between 士道は頬に汗をひとすじ垂らした。and 士道は頬に汗がひとすじ垂れた。?
Thank you.

 

[Toritoribe]

When describing an action of one's body part, "body part を transitive verb" is the most common structure, whether it's volitional or non-volitional action. 汗, 涙, 声 or like that also work as body parts.
e.g.
彼は両手をひろげた。
彼女は両目から涙をこぼした。
太郎は大声を出した。

"Subject は body part が intransitive verb" works as a kind of は・が文, which expresses the subject's characteristics/ability, for instance 象は鼻が長い or 彼は足が速い.
e.g.
彼は両手がひろがった。(he had an ability to outspread his arms.)
彼女は両目から涙がこぼれた。(She had an ability to drop tears from her eyes.)
太郎は大声が出た。(Taro had an ability to shout.)

Needless to say, "body part が/を potential form" is usually more common for this meaning
e.g.
彼は両手が/をひろげられた。
彼女は両目から涙が/をこぼせた。
太郎は大声が/を出せた。

Since the problem is は, there is no problem to express an action if は isn't there. The following three sentences are valid as a description of an action.
e.g.
彼の両手がひろがった。
彼女の両目から涙がこぼれた。
太郎の口から大声が出た。

Also, it's OK if ～のを感じた, ～のに気付いた or something like that is put at the end of the sentence, because は works as the subject marker of that verb.
e.g.
彼は両手がひろがったのを感じた。
彼女は両目から涙がこぼれたのに気付いた。
太郎は大声が出たと信じた。

As for your sentence, it's awkward since 頬に汗がひとすじ垂れた can't be 士道's characteristics/ability. The following sentences are no problem, as I wrote so far.
e.g.
士道の頬に汗がひとすじ垂れた。
士道は頬に汗がひとすじ垂れたのを感じた。
士道は頬に汗がひとすじ垂れたのに気付いた。

 

[zuotengdazuo]

Thank you so much. Very informative and helpful explanation.
So can I think the two sentences 士道は頬に汗をひとすじ垂らした。and 士道の頬に汗がひとすじ垂れた。are the same?

 

[Toritoribe]

The meaning is identical, but the nuances are different.

The latter is a neutral description of an action. It just describes a scene objectively as it is.

On the other hand, the former, i.e., the original one is a description about 士道. Even if it's a non-volitional action, it somehow suggests that the cause/reason of the action 汗をひとすじ垂らす was on him, for instance, he was in a tense state. These kinds of expressions are often used in the narrative part of a novel when describing a scene from the viewpoint of the topic (士道 in this case).

 

[zuotengdazuo]

Thank you again! I see.

 

[zuotengdazuo]

Hi, Toritoribe-san, can I ask about another similar sentence?
そこでようやく士道が起きていることに気づいたのだろう。士道のお腹の上に足をのっけていた妹ーー琴里が、中学校の制服を翻しながらこちらに顔を向ける。

I think your explanation in post #2 also applies to the underlined clause—— 中学校の制服 can be work as a body part and even if the action 翻す is a non-volitional action in this context, we should use を before 翻すhere because the clause implies that the reason why the uniform fluttered is that 琴里 turned her head (こちらに顔を向ける). So 制服が翻る would be unnatural here. Am I on the righ track?

 

[Toritoribe]

Yes, you got it right. 中学校の制服が翻りながら、琴里がこちらに顔を向ける。 sounds odd because the relation between the two actions is unclear.

制服が翻る can work in an objective description.
e.g.
琴里がこちらに顔を向ける。中学校の制服が翻っている。

This description is natural, but it's not stated that the action/movement "fluttering" is caused by 琴里's action (it could be done by wind, for instance), and it can't have the meaning of ながら "while doing".

 

[zuotengdazuo]

Thank you again. I see.