This is the song mentioned in Revelation 14 that Milton is continually alluding to and we saw him allude to just this passage in Ad Patrem.

这时《启示录》第14卷里面提到的4,弥尔顿一直在暗指这一段,他在Ad，Patrem中也暗指了这一段。

耶鲁公开课 - 弥尔顿课程节选