Kepler

What It Is Like to Look through a Telescope for the First Time?

MA History & Philosophy of Science

Jürgen Stowasser

January 2024

Primary Sources

https://kepler.badw.de/kepler-digital.html

https://kepler.badw.de/die-edition.html

Johannes Kepler, Gesammelte Werke

Astronomical & Optical Works: Dissertatio cum Nuncio Sidereo (1610)
Narratio de observatis a se quatuor Iovis satellitibus (1611)
Dioptrice (1611)
Harmonices Mundi Libri V (1619)
De Cometis libelli tres (1619–1620)
Astronomischer Bericht Von Zweyen im 1620. Jahr gesehenen Mondsfinsternussen

Astrological Writings: Tertius Interveniens (1610)
Calendaria et Prognostica
Manuscripta astrologica
Somnium Seu Opus posthumum de Astronomia Lunari (1634)

Correspondence:
XIII: Briefe 1590–1599 (1945)
XIV: Briefe 1599–1603 (1949/2001)
XV: Briefe 1604–1607 (1951/1995)
XVI: Briefe 1607-1611 (1954)
XVII: Briefe 1612-1620 (1955)
XVIII: Briefe 1620-1630 (1959)

Perspicillum (Telescopium Belgicum)

Looking Through
Looking At
Measuring & Mapping

Making Astrology (Somehow) Work

"So that, as I have written once in this matter, Astrology, the foolish daughter, feeds and sustains her most wise but poor mother, the Astronomy."
[...] ut (quod olim in hac materia scripsi) Astronomiam matrem sapientissimam, sed pauperculam, stulta filia Astrologia [...] alat et sustentet. Johannes Kepler, Tabulae Rudolphinae. Gesammelte Werke X. München 1969, p. 40.

Sincere astrologers should never be precise in their predictions or name specific dates (unlike fraudulent starmongers).

Reading Kepler's astrological as "hybrid" of different fields of knowledge & epistemological claims:

By integrating information from other domains, he achieves a higher probability of his predictions, e.g., annual Calendaria et Prognosticadraw from weather lore and agricultural knowledge; peasants would know "Astronomiam ex instinctu" (IV: 244) and have a more accurate perception of nature than astrologers (XI/2: 160)

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