「んだ」の使い方について質問させていただきます


I would like to ask you a question about the usage of んだ. I know that it can
be used to explain a situation, but I have noticed it can be used to bring up
a topic as well, is it true? I heard the following sentence: 仕事やめたんだ In this
case I do not think んだ is used to explain a situation because the speakers
were talking about a totally different topic. Also, what is the difference
between 仕事やめたんだ and 仕事やめた when you want to bring up a topic?

Thank you in advance!




んだ/のだ is used give a supplemental explanation (補足説明{ほそくせつめい})- it is an
explanation but not always necessary.

> (Xは)仕事{しごと}をやめた。(X depends on the context)

This is describing only the fact that X has quit a job. This is just a
statement by the speaker, there is no nuance that the speaker is giving an
explanation.

> (Xは)仕事{しごと}をやめたんだ。

Using んだ/のだ to '仕事{しごと}をやめた' creates a nuance that the speaker would like to
tell the story about why or how X quit the job. This is a big difference from
から (e.g. 仕事{しごと}をやめたから) which is normally used to explain a situation.

