[Analysis - NO.]
"Mournful numbers": Science. The application of scientific principles would bring one to the conclusion that death brings an end to life; and, by definition a cessation of all functions of a living being, including, the capacity to dream. However, in this opening stanza, Longfellow immediately declares himself to be a believer in life hereafter. Human life, he declares, would not be life without the belief (the dream) of life hereafter. It is not clear how Longfellow might be able to support this conclusion, viz., life is not life without a belief in the hereafter? Further, Longfellow dismisses rational argument by expressing the view that some things are beyond the comprehension of mere mortals.]
"Life is but an empty dream!"
For the soul is dead that slumbers,
And things are not what they seem.