Nature of any kind thrives on forward progress. And progress for a rational mind means not accepting falsehood or uncertainty in its perceptions, making unselfish actions its only aim, seeking and shunning only the things it has control over, embracing what nature demands of it—the nature in which it participates, as the leaf's nature does in the tree's.
Except that the nature shared by the leaf is without consciousness or reason, and subject to impediments.
Whereas that shared by human beings is without impediments, and rational, and just, since it allots to each and every thing an equal and proportionate share of time, being, purpose, action, chance. Examine it closely. Not whether they're identical point by point, but in the aggregate:
this weighed against that.