In a way the "'"smelling trees"'" is a metonymy because it has substituted Caddy"'"s innocence.
The last clause, '"'and I began to cry,'"' is the final downfall of this sentence. These clauses are arranged to climax. Faulkner wants to focus on Benjy crying, the final result of Caddy"'"s promiscuity and marriage, so he writes the preceding clauses to build up to it. Now the reader can see that the first clause was a form of false hope. Caddy gave Benjy the sense that she was going to protect him, but she was getting married and leaving. She had also gotten pregnant outside of wedlock and this caused Benjy great sadness. He was not fooled by the hug because he could smell that the scent of trees was no longer there.
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