In fact, there's nothing that keeps its youth, So far as I know, but a tree and truth.
 Oliver Wendell Holmes Sr., The Autocrat of the Breakfast-Table (1858). copy citation

Context

“Running as usual; much the same. Thirty and forty at last arrive, And then come fifty, and fifty-five. Little of all we value here Wakes on the morn of its hundredth year Without both feeling and looking queer. In fact, there's nothing that keeps its youth, So far as I know, but a tree and truth. (This is a moral that runs at large; Take it.—You're welcome.—No extra charge.)
First of November,—the Earthquake-day.— There are traces of age in the one-hoss-shay. A general flavor of mild decay,” source

Meaning and analysis

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