Linguists these days tell us that an author chooses one synonym over another for reasons of meaning (one may be slightly more specific or general than the other), for reasons of common usage (one of several synonyms may be used more commonly in certain contexts), or for stylistic reasons.

All true.  To which I would want to add that an author may choose one synonym over another for reasons of sound (alliteration, assonance), or even shape (one word looks “smoother” on the page and thus conveys “smoothness” along with everything else it conveys; dittos with “prickly” looking words, etc.), or for reasons of rhetoric (a word choice may not only convey information but also nudge the reader to think about the information in a certain way), or for reasons of historical/cultural associations.

For instance:

“Quartz contentment,” says Dickinson.  Why “quartz”?  That’s a pretty specific word, without real synonyms, but we can think of words that might carry some of the same semantic load.  ”Granite contentment” or any other hard mineral would do some of the same work; “diamond contentment” would convey both the hardness and “crystalline” sense of “quartz.”  So, why quartz?  I suspect because it sounded better.  The near-alliteration of the phrase makes it more lovely, more memorable, more penetrating than the alternatives.  The hard q/c alliteration also conveys some meaning.  ”Quartz contentment” feels sharp-edged, not content at all, not soft.

Or: Should I call that small house a “lodge” or a “hut” or a “cabin” or a “cottage” or a “bungalow”?  One might find tiny lexical differences between the words, but those lexical differences don’t decide the choice.  More likely, the choice would be determined by differences of historical associations.  ”Cabin” tends to put us on the frontier; “lodge” in the Alps; “hut” feels more cramped, smaller, quite rustic and rough; “cottage” and “bungalow” are small but cozy, evoking a Wordsworthian tremor in the soul, especially if you add a wisp of smoke curling from the chimney and set it in the middle of a thick forest.