When Wren began his professional career in astronomy, a hundred years had passed since the Copernican theory was first tentatively expressed in English through Robert Recorde's Castle of knowledge, published in 1556. Recorde had also represented the beginnings of the wider domain of the mathematical sciences, so that the ‘new astronomy’ in England began and developed within this tradition.

It had been a crucial period for astronomy throughout Europe too. If the Copernican theory had not exactly triumphed by the mid-seventeenth century, the Ptolemaic had certainly been replaced as the conservative alternative by the Tychonic where Sun and Moon revolved around a stationary Earth and the planets revolved around the Sun; or by the so-called semi- Tychonic system which accepted a rotating Earth but retained the annual orbit of the Sun. But for astronomers in the vanguard of contemporary debate, a change had occurred more fundamental than the mere juxtaposition of planets in a geometrical problem. With Kepler's Astronomia nova a whole new concept of the nature of astronomy had emerged – astronomy, not only as mathematical theory but also as ‘celestial physics’. For Kepler, a mathematical model had to be interpreted in terms of a physical mechanism. Though for him the model, of itself, still had an important explanatory function, his work led to the notion of planetary theory, rendered intelligible, not through its underlying geometrical principles as it had been from Eudoxus to Copernicus, but through a causal hypothesis.