By extension we have our attempt as readers to arrive at an understanding of the first two books in general.

延伸开来，我们作为作者，试图,达成对这两卷书的大体上的理解。

耶鲁公开课 - 弥尔顿课程节选

The footnote to your Norton here suggests that the gazebo is a summerhouse and by extension it's quite an extension the nationalist movement, and then, "even the whole temporal world."

书上的注释说,楼台指的是凉亭,可引申为民族主义运动，“甚至整个现世世界“

耶鲁公开课 - 现代诗歌课程节选

But we usually mean by it the immediate, the nuclear family, with some extension.

但通常都是指直系亲属，核心家庭，少量分支。

耶鲁公开课 - 新约课程节选