Yeats is talking about an event that has brought forth destruction, destruction of the world before the Easter Uprising.

叶芝描绘了这样一个事件,它带来了毁灭，对复活节前世界的毁灭。

耶鲁公开课 - 现代诗歌课程节选

It was from out the rind of one apple tasted, that the knowledge of good and evil, as two twins cleaving together, leaped forth into the world.

这是从那个被咬的苹果皮外来的，善恶的知识，像一对双胞胎分开但又在一起，一起在人间前进。

耶鲁公开课 - 弥尔顿课程节选