Analysis of The Weakest Thing

Which is the weakest thing of all
Mine heart can ponder?
The sun, a little cloud can pall
With darkness yonder?
The cloud, a little wind can move
Where'er it listeth?
The wind, a little leaf above,
Though sere, resisteth?

What time that yellow leaf was green,
My days were gladder;
But now, whatever Spring may mean,
I must grow sadder.
Ah me! a leaf with sighs can wring
My lips asunder -
Then is mine heart the weakest thing
Itself can ponder.

Yet, Heart, when sun and cloud are pined
And drop together,
And at a blast, which is not wind,
The forests wither,
Thou, from the darkening deathly curse
To glory breakest, -
The Strongest of the universe
Guarding the weakest!