What he says is exactly what he means. He talks of the only thing that he knows, the garden. The garden is his surroundings, its his life, its who he is, its all he knows. He grew up around it. This quote proves that Chance and everyone else doesn't interpret things the same way because they both mean it in different ways.
Chance uses the metaphor of the garden without knowledge of it.
He is unaware that he is using it because to him, what he says is exactly what he means. Chance is affected by people's misconception of what the garden really represents. He wouldn't have popularity, or be seen on T.V., or even be a candidate for president. This is shown when Chance is being considered a candidate for President. This quote proves that if it wasn't for the misunderstanding, then Chance wouldn't eventually be a possible candidate for President.