"Of a thousand or ten thousand attempting to
enter by this Gate,
Only three or perhaps five pass through" Master Huang-po
James Austin of "Zen and the Brain" thinks that Huang-po had pretty rigorous criteria and probably intended this to represent the number who attained 4th Path. He mentions a survey of Americans in which 18 percent reported they had had a mystical experience in which they "felt they were very close to a powerful spiritual force that seemed to lift them outside themselves" and 12 percent had had such an experience more than once. Probably this represented the A&P for most of those people though.
He mentions that in a traditional Rinzai monastery that monks were expected to reach some level of kensho (Stream Entry) after two to three years of training, It was expected that it might take another 10-15 years before they fully matured. This was confirmed in a conversation with Kobori-roshi who told him that it would usually take three years "to get through the Gate," and following this he said "But not into the temple yet." He estimated it would require another ten to twelve years before the wakened monk became skillful enough to teach other monks, at least in the rigorous Rinzai tradition.
Dogen estimated one or two out of several hundred or even a thousand disciples who became truly enlightened, even after they had trained with a great Zen master - but again, he was probably referring to 4th Path as elsewhere he says, "A person who gives rise to a real desire and puts his utmost efforts into study under a teacher will surely gain enlightenment... Those who have this drive, even if they have little knowledge or are of inferior capacity, even if they are stupid or evil, will without fail gain enlightenment."
Ona Kiser wrote:
what's kind of mystifying and delightful to me is seeing so many,many seekers who never seem to see beyond their own noses for decades, and at the same time many who see quite clearly in short order. how? who? why? no one knows.
cynthia bourgeault, a christian contemplative who crosses over into the buddhist geeks circles (so does david frenette) said she saw a survey that about 15 percent of active christians have a private practice of personal prayer/meditation.
This is a helpful statistic - so most of those people will get it, if they stick with it - we have no idea of how long those people maintain though or how consistent their practice is...
Austin elsewhere suggests that the degree of suffering that a person experiences may have something to do with whether they get it or how soon...