Douglas Gwyn explains it for us

I have been slowly making my way through Douglas Gwyn's Apocalypse of the Word: The Life and Message of George Fox. It was his first book, I believe, published in 1986 by Friends United Press, and based on his doctoral dissertation. I've read most of his other books and yet had never tackled this one. It's taking time because I keep setting it aside to read other books, or to play with my kids or hang out with my wife or get ready for Affordable Housing Week.

Anyway, this passage practically leapt off the page at me, so here it is, from page 173 of the 1986 edition:

There is a popular notion, even among some Friends, that the Quaker "brand" of worship is not for everyone; that it requires a cool, detached, middle- to upper-middle class Anglo-American temperament. Not only is this notion implicitly classist and racist, it constitutes a terrible misunderstanding of what Quaker worship means. What makes this worship difficult for people of all races and temperaments to accept is the way it brings the experience of the cross into worship itself. No one takes up this cross easily. Yet it is in this quiet, sometimes desperate, prayerful attitude that one may give up one's self to God and say, "nevertheless, not my will, but thine, be done" (Luke 22:44).