G.K. Chesterton, the master of the aphorism, had this to say: "The Protestant generally says, 'I am a good Protestant,' while the Catholic always says, 'I am a bad Catholic.' "
The source is "Irish Impressions", one of G.K.C.'s best "travel books". I would be surprised if Percy hadn't read it.
You need the context of course, but it goes on for pages, which wouldn't do here. Here's a bit of it, though: "Any honest man has a right to think he is right. But to think he is good, not to say great, no honest man can reach that comfortable conviction without a course of intellectual dishonesty."
Yes, I'm the Chesterton guy. Did you like our Web Site? Any suggestions?