Sometimes you can't control what goes on in your thoughts, like who you like. That just seems to happen without warning. While this doesn't exactly happen with leaves, it's an involuntary response.
If leaves could 'control' how they shifted colors, and people could 'control' what goes on with their bodies and minds, life would start to become predictable. Some of the beauty in autumn lies in seeing what colors the leaves end up being, and the beauty in life is that it takes its own course with everyone- just like every tree's leaves fall at their own pace.
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