Useful, cynical, and better than the industry that adopted it.

Everyone hands this to salespeople and account managers, which is roughly like handing a lockpicking manual to a locksmith. It's wasted there. The right reader is the person being sold to, and the right moment for it is the week before you buy a car.

What's good is the discipline. Six principles, each defined narrowly enough that you can go out and look for it, each tested somewhere unglamorous: a charity mailing, a cocktail waitress, a queue at a photocopier. There's an intellectual modesty there that the whole airport-psychology aisle has since abandoned — he tells you how large the effect was, and he tells you when it failed.

My quarrel is that reciprocity and commitment end up explaining so much that scarcity and liking start to look like the same animal in different coats. Give me a seventh chapter arguing against the taxonomy rather than defending it.

Two things stuck. First, that a small free gift you never asked for creates an obligation you never agreed to, which is why I now refuse the pen. Second, the material on consistency: get someone to say the small yes in public and the large yes follows almost by itself. I caught myself doing exactly that to Neil last spring and stopped mid-sentence, ashamed of the technique and slightly proud of the execution.

Eight. It's forty years old and the newer books citing it are all worse than it is.