Hi, I'm Peter Adamson, and you're listening to the History of Philosophy podcast, brought to you with the support of the Philosophy Department at Kings College London and the LMU in Munich, online at historyofphilosophy.net.

Today's episode, music of the Spheres, Johannes Kepler.

Over the last couple of episodes, I've been trying to place two great astronomers of the 16th century within the context of that time.

But rather ironically, it's only now that we come to a third great astronomer, who lived well into the 17th century, that the intellectual currents of the Renaissance become impossible to ignore.

Johannes Kepler was born in 1571 and died only in 1630, meaning that his life overlapped with that of figures like René Descartes and Thomas Hobbes, but then Hobbes lived to be 91 years old, so overlapping with him was easy to do.

Certainly some aspects of Kepler's thought seem at home in the 17th century, his repeated comparison of the cosmos to a clock, fits with the mechanistic conception of nature we find in Descartes and other enlightenment philosophers.

But in most respects, Kepler comes across as a figure of the Renaissance and Reformation period.

Like Lipsius, his career was shaped by conflict between Protestants and Catholics.

Like Melanthon, he was himself a deeply pious Lutheran, who saw astronomy and astrology as the ideal route to the knowledge of God.

And speaking of ideal, he was, like Nicholas of Cusa and Marcelo Fichino, a Platonist.

In one of his most important works on the harmony of the world, Kepler credits Plato with the idea that God, the actual fount of geometry, practices eternal geometry and does not stray from his own archetype.

You could hardly do better as a statement of Kepler's own intellectual project.

We can begin his story by picking up where we left off last time.

At the end of his life, having lost favor with the Danish court, Tiko Brahe had moved to live near Prague.

Here he took on the young Kepler as an assistant.

Kepler had already been shaped by his studies in Tübingen, where Melanthon's ideas shaped the curriculum.

Despite curricular and religious reform, Aristotle was still a fundamental author there, and Kepler was very familiar with his works.

He had sufficiently strong ancient Greek to second-guess translations of Aristotle's metaphysics.

And when he came to defend Copernican Haleo-Centrism, he referred to Aristotle for evidence that this view had been anticipated by the Pythagorean.

As this shows, Kepler was shaped by the humanistic values of Tübingen, which included the study of mathematics as a classical science that needed to be revived or restored, remember that this rhetoric was also used by Brahe.

The most significant influence on him was probably that of his mathematics professor, Michaela Mastlin.

As we saw, Mastlin defended a realist version of the new Copernican astronomy.

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