To begin with, Henry Longfellow uses nature in contrast with a persons lifetime. In "The Tide Rises, the Tide Falls", Longfellow gives the logical impression that nature repeats its cycle without foreseeable end, while a persons lifetime is limited. An example to this can be found in the last stanza where he writes: " The day returns, but nevermore, Returns the traveler to the shore". Longfellow associates darkness with death, ocean with life, and light with heaven. In other words, he is stating that once one reaches death, sometimes they are forgotten, but no matter what, they will never return to life. On the contrary, Longfellow does not want to give the idea that death should be feared. Instead, he simply wants one to be aware that death is indeed coming.
Furthermore, William Bryant uses nature as a form of motivation to comfort ones fear of death. In the beginning of "Thanatopsis", the meaning of the poem is pretty much stated. "To him who in the love of nature holds communion with her visible forms", simply reads that if one is in communion with nature, then nature will give you a message. The message will tell one how to live ones life, and it will be unique to everyone else who is in communion with nature. Hence,nature is ones friend. Secondly, in the third stanza, Bryant attempts to make death a comfortable feeling, referring to the word couch, as something you curl up and feel good in. He does this so that one can see that death should be anything be fearful.
In sum,