I mean that in two ways. Of course, what they have to say about their primary subject is rich and savory.
But even their "incidentals," their supporting illustrations and arguments, reveal that they have thought long and hard about other subjects as well, and it makes one want to read them discourse on those other subjects as well.
C. S. Lewis was such a thinker. In ch. 2 of Letters to Malcolm: Chiefly on Prayer, he responds to the charge that praying in one's own words is far better than praying the ready-made prayers of others. Lewis argues that both have value, and, while he prefers praying in his own words, he finds that also praying the "ready-made" prayers of others preserves a sort of balance to his prayer life, and he explains why.
Lewis argues his point well, and I can't say I disagree in the least, (which is why I have enjoyed using prayer books myself, like The Valley of Vision and A Diary of Private Prayer).
But not only does he argue his subject well, he drops other thoughts in support of his argument, thoughts which reveal that he has spent much time thinking about a lot of things.
- "Heaven will display far more variety than Hell."
- "The more 'up to date' the book is, the sooner it will be dated."
- "I think the 'low' church milieu that I grew up in did tend to be too cosily at ease in Sion [sic]. My grandfather, I'm told, used to say that he 'looked forward to having some very interesting conversations with St. Paul when he got to heaven.' Two clerical gentlemen talking at ease in a club! It never seemed to cross his mind that an encounter with St. Paul might be rather an overwhelming experience even for an Evangelical clergyman of a good family ..."
I find these statements tantalizing. Who knows if I'll ever get through Letters to Malcolm? If I read it too fast, I may miss a lot.