An imagined gathering

An evening at Bellosguardo

1628 · Florence, Italy

Galileo shows his telescope to Kepler and a young Descartes, and the three of them argue about what the instrument can prove.

Galileo's villa at Bellosguardo looks out over Florence, and he has set up his best telescope for the evening. Kepler, whose eyesight is poor, listens as Galileo describes the mountains on the moon; Descartes, then thirty-two and on a tour of Italy, has come out of curiosity about the man and the instrument.

The talk moves from what the telescope shows to what it can be trusted to show, and from there to the foundations of knowledge itself. Descartes is already turning over the doubt that will consume him; Galileo wants certainty from observation, and Kepler wants it from geometry. They eat a pullet, a herb pottage, and marchpane, and part without resolving anything, which none of them minds.

The table

Host: Galileo Galilei

Johannes KeplerImperial mathematician, whose poor eyesight makes him a careful listener.

René DescartesYoung French philosopher and mathematician, travelling in Italy.

The menu

a period dish

First course

Herb Pottage

a period dish

Dessert

Marchpane

a period dish

a period dish

Discussed

Telescopic astronomy

Galileo Galilei

What Galileo saw through his improved spyglass — lunar mountains, Jupiter's moons, the phases of Venus — and why it unsettled the received cosmos.

Cartesian doubt

René Descartes

Descartes' method of doubting everything that can be doubted until he reaches the one certainty that he is thinking.

This gathering is an editorial recreation grounded in the biographies of those present; it did not necessarily take place as described.