Ruskin on Personalized Pricing

There are few bargains in which the buyer can ascertain with anything like precision that the seller would have taken no less; — or the seller acquire more than a comfortable faith that the purchaser would have given no more. This impossibility of precise knowledge prevents neither from striving to attain the desired point of greatest vexation and injury to the other, nor from accepting it for a scientific principle that he is to buy for the least and sell for the most possible, though what the real least or most may be he cannot tell.

John Ruskin, Unto this Last, and Other Writings 197 (Clive Wilmer, ed. Penguin Classics 2005) (1862).