Many men believe not themselves what they would persuade others; and less do the things which they would impose on others, but least of all know what they themselves most confidently boast.
Many men believe not themselves what they would persuade others
Many people try to make other people believe things that they, personally, do not believe. This is called hypocrisy. For example, a politician who says drugs are immoral, while secretly indulging in cocaine.
and less do the things which they would impose on others,
Even fewer people do the things that they want to make other people do. For example, a politician who sends soldiers to war, while avoiding military service himself. It is hard to find someone who will put their money where their mouth is.
but least of all know what they themselves most confidently boast.
The people who talk loudest and most confidently don't know what they're talking about. For example, almost anything a politician says in a debate. Jonson thinks it is rare to find someone who boasts for a good reason.
In short, I think Ben Jonson was talking about politicians!
According to Austen Saunders in a blog at http://spectator.uk.co, the quotation is from a collection called
Timber: or Discoveries; Made Vpon Men and Matter: As they have flow’d out of his daily Readings; or had their refluxe to his peculiar Notion of the Times.
The quotation is a peal of cynicism, a blistering condemnation of hypocrisy.
Many people don't believe what they urge others to believe, don't do what they wish others to do, and don't know the things that they want others to think they know..
(The trouble with paraphrasing Jonson is that you end up making bad language out of good.)
The next line is a peach:
Only they set the sign of the cross over their outer doors, and sacrifice to their gut, and their groin in their inner closets.’