Read the following poem by Edgar Allen Poe and answer the question that follows. 
 A Dream Within a Dream Take this kiss upon the brow! 
 And, in parting from you now,
 Thus much let me avow‚ 
 You are not wrong, who deem
 That my days have been a dream: 
 Yet if hope has flown away 
 In a night, or in a day, 
 In a vision or in none, 
 Is it therefore the less gone? 
 All that we see or seem 
 Is but a dream within a dream.
 I stand amid the roar
 Of a surf-tormented shore, 
 And I hold within my hand 
 Grains of the golden sand‚
 How few! yet how they creep 
 Through my fingers to the deep 
 While I weep‚while I weep! 
 O God! can I not grasp
 Them with a tighter clasp?
 O God! can I not save 
 One from the pitiless wave? 
 Is all that we see or seem 
 But a dream within a dream? 
 What, if anything, does the sand in this poem symbolize? Defend your answer in at least three complete sentences.