Answer:
It introduces an ominous tone that accentuates how dreams create anguish.
Explanation:
Some of the words from the stanza say that dreams are as irretrievable as sand, it goes further to say that it's long knife glittering in its teeth. This tone shows that dreams have the power to create anguish. It gives off a tone with the impression that causes us to worry that something bad or evil is about to happen as we read through the stanza, especially the part where he knife is described to claim it's patrimony.
Not Waving but Drowning Theme of Death. You'd think that there couldn't be a clearer distinction than the one between life and death, but "Not Waving but Drowning" goes out of its way to muddy the water, so to speak. The focus, after all, is a talking corpse who just won't shut up even though the living can't hear him.
The answer would be dialect
