Feet, of course, has a lot of meanings, and Milton's poetic feet, the material of the verse written in six and eight and ten syllables in this poem, are also in 1634 printless -- they're unpublished.

双脚，当然有很多意义，而弥尔顿富有诗意的双脚,这首六，八，十音节的诗，在1634年也是不留痕迹的--因为那时候还没有出版。

耶鲁公开课 - 弥尔顿课程节选