Here, in the quiet of Boldwood’s parlour, where everything that was not grave was extraneous, and where the atmosphere was that of a Puritan Sunday lasting all the week, the letter and its dictum changed their tenor from the thoughtlessness of their origin to a deep solemnity, imbibed from their accessories now.
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Love whom you will but marry your own kind was a dictum amounting to instinct within her.
Harper Lee -- Go Set a Watchman
I don’t even remember where I learned that childhood rhyme or the dictum that demanded you scratch your head every time you heard a siren, lest the next siren be for you.