Laws are sand, customs are rock. Laws can be evaded and punishment escaped, but an openly transgressed custom brings sure punishment. The penalty may be unfair, unrighteous, illogical, and a cruelty; no mater, it will be inflicted, just the same.

Mark Twain (1835-1910) American writer [pseud. of Samuel Clemens]

Essay (1906), “The Gorky Incident,” Letters from the Earth (c. 1909; pub. 1962) [ed. DeVoto (1939)]
    (Source)

Commenting on the eviction of Maxim Gorky from multiple hotels in New York City because the woman he was traveling with was not his wife. Twain was a supporter of Gorky's efforts to foment revolution in Tsarist Russia.

The essay was not published in Twain's lifetime. It's original publication was in the Slavonic and East European Review (1944-08), also edited by DeVoto.