CHRISTIAAN H UYGENS SAT at the head of the table, the perihelion of the ellipse, and Daniel Waterhouse sat at the opposite end, the aphelion. Nicolas Fatio de Duilliers and Eliza sat across from each other in between. A dinner of roast goose, ham, and winter vegetables was served up by various members of a family that had long been servants in this house. Eliza was the author of the seating plan. Huygens and Waterhouse must not sit next to each other or they'd fuse together and never say a word to the others. This way was better: Fatio would only want to talk to Waterhouse, who would only want to talk to Eliza, who would pretend she had ears only for Huygens, and so the guests would pursue each other round the table clockwise, and with a bit of luck, an actual conversation might eventuate.