It said the forests and undergrowth were so dense, no one could get through them.

VOA: special.2009.07.20

As you have no doubt experienced, this is a dense and difficult poem, so please reread it innumerable times for Wednesday's class, and in addition to that do the other readings assigned.

你们肯定也觉得了，这首诗很复杂很难懂，所以要一遍一遍的重复读，准备好周三的课，也要读布置的其他材料。

耶鲁公开课 - 弥尔顿课程节选