I've been publishing newsletters for a while now. I know what I'm doing, I think. I know my readers. I know the topics that land well and the ones that fall flat. I know the rhythm of a good email subject line and how to open a piece without wasting the first sentence. Or so I thought. Then I read a 1916 business parable about a man called Oliver Adams, and I realised I had been making a mistake that is, in retrospect, completely obvious.

The mistake is this: I had been writing for paper-makers. Not literally. But Adams, in the book — Robert Updegraff's Obvious Adams — visits a bond paper manufacturer and comes back with advertising copy that describes how the paper is made: carefully selected white rags, pure filtered water, hand inspection of every sheet. The manufacturer is unimpressed. "Every good bond paper is made that way," he says. Adams asks: "To whom are you advertising — paper-makers or paper-users?" The manufacturer has been in the trade so long that the most compelling facts about his product have become invisible to him. He assumes everyone knows them. Nobody does.

I read that and stopped. I have been doing exactly this. I publish newsletters on business, journalism, AI, and the mechanics of building an online audience. These are subjects I have spent 40 years studying. The things I take for granted — the things I don't bother to explain because they seem obvious — are frequently the most useful things I know. And I have been leaving them out because they felt too basic to mention.