My words echo
Thus, in your mind.But to what purposeDisturbing the dust on a bowl of rose-leaves
I do not know.
In these 23 words Eliot is saying that his act of composing the words of Burnt Norton is, by the time you read this, part of the destroyed past. His words only exist in the mind of you, whoever you are, who happen to be reading this poem in this microsecond of time. Conversely from his point of view you, reading this, are just a vague potential in the abyss of non-existence that lies in front of him. So the poem is a message from a destroyed man to a reader who does not exist. The bowl of dusty old rose leaves seems to make the words you read the dried husks of a living act of creation, now long dead, and the listless breeze of your attention just lifts them momentarily in a parody of life.
The first time I wrote about Burnt Norton egretplume said it 'reminds me of the SF world of alternate realities'. I agree. I think Burnt Norton is very much like SF. It says to you 'Look - the real universe is extremely peculiar and rather dreadful. The conventional model you have of existence is not only quite dull, but completely wrong.'
The dried rose leaves are also a bridge into the next section which is about walking into the living rose garden at Burnt Norton.