Regard for sincerity in Western civilization has ebbed and flowed since those 16th-century Protestants began plumbing their inner selves. (“I have within me the great pope, Self.” — Luther) Magill charts these cycles of action and reaction.
The problem with a community dedicated to sincerity is that impostors will quickly learn the appropriate outward show. As the old showbiz adage has it: “Sincerity — if you can fake that, you’ve got it made.” (I have a feeling that one’s a favorite with political consultants, too.) La Rochefoucauld noted in 1665 that: “What usually passes for sincerity is only an artful pretense designed to win the confidence of others.”
So the tide ebbed, and a mannered society, elevating the courtly arts of wit, style, flattery, and guile made a comeback, the restoration of the English monarchy in 1660 standing as a convenient milestone.