The most important piece of symbolism used in this poem is the idea, and picture of death. The entire poem is based around the sole idea of death, it's inevitableness, and the foreboding nature of man's demise. The nature of death is the sole theme and central idea behind the entire poem. The line "So live, that when they summons comes to join The innumerable caravan which moves To that mysterious realm, where each shall take His chamber in the silent halls of death," is the best example of the poem's theme. The line explains that when your time has come you should accept it without quarrel and take your place in the hall of death by becoming one with nature and all those who have passed before you and will pass after you.
The morbid and morose theme of the poem helps deliver the meaning in a much more effective way. The cold and calculating emotion central to the poem helps deliver the meaning of the poem and support it's idea of death. The message of the poem, while depressing and bleak, is optimistic under the surface. The idea that one will become one with Earth and all those who have passed or will pass is a hopefully and spirit lifting idea that should leave the reader with a positive outlook on the subject matter of passing away. The poem was extremely effective due to it's methods of using emotion and getting it's point across.