Get out the microscope, because we’re going through this poem line-by-line.
Nor mouth had, no nor mind, expressed
What heart heard of, ghost guessed:
- The speaker says that the sources of sadness are difficult to "express," either for the very young, like Margaret, or for older people. In other words, you can't describe it with words ("mouth"), or even in your thoughts ("mind").
- But your "heart" knows the reasons, and your spirit, or "ghost," can guess them.
- "Ghost" here might also be a reference to the "Holy Ghost" of Christianity—Hopkins was a devout Jesuit. Read the "In a Nutshell" section for more on Hopkins's religion.
- Notice those M, H, and G words paired up here? Yup, that's some more alliteration for you.