词汇与表达：gist-motif-subject-theme-mythos

I'm afraid I don't quite follow your gist (= what you really mean) .
对不起，我还不太明白你的意思。
Then I interpreted the gist and purpose of this paper.
接着，笔者阐释了论文的主旨和目的。
American Dream is one of the most important motifs of American literature.
美国梦是美国文学最重要的母题之一 .
A wedding is the perfect subject for video.
婚礼是极好的录像主题。

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North American literature is the main theme of this year's festival.
北美文学是今年艺术节的主题。

Water is the city's mythos.
水是城市的主题。