As we have seen in our last posting in this blog Copernicus, who postulated a model in which the sun was at the centre of the universe. knew that the clear advantages of his model would not protect him from the hostile reaction of the orthodox authorities and the Inquisition, and it was not until 1543 – the year of his death – that he eventually published his complete work On the Revolutions of the Heavenly Spheres.

It is clear from the extent of the criticism of his work that Copernicus challenged not only the knowledge of the cosmos, as portrayed by the church, but he challenged knowledge itself: Should our impartial experience determine our understanding, or is it our knowledge that the world should conform to?

For example, Tolosani, a contemporary of Copernicus, wrote:

[Copernicus] seems to be unfamiliar with Holy Scripture since he contradicts some of its principles, not without the risk to himself and to the readers of his book of straying from the faith. ... in his imagination he changes the order of God's creatures in his system. ... he seeks to raise the Earth from its lower place to the sphere where everybody by common consent correctly locates the Sun's sphere, and to caste the sphere of the Sun down to the place of the Earth, contravening the rational order and Holy Writ, which declares that heaven is up, while the Earth is down.

It was most likely, therefore, that the Church would have condemned Copernicus’ work, had it not been for an introduction inserted by the publisher. The introduction stated that the book merely presented a simpler way to calculate the positions of heavenly bodies, and that “the hypotheses contained within made no pretense to truth that, in any case, astronomy was incapable of finding the causes of heavenly phenomena.” This unauthorized insertion, although appalling to many, ensured the book was not immediately condemned. In fact, it was publicly available for over 70 years before it was subject to censorship.

Although some were sentenced to death for their support of Copernicus’ heliocentric system (for example, Giordano Bruno was burnt alive in 1600) it was not until 1616 that the Church placed the work on the List of Prohibited Books (Index Librorum Prohibitorum) and decreed that “the propositions that the Sun is immobile and at the center of the universe and that the Earth moves around it, judging both to be ‘foolish and absurd in philosophy,’ and the first to be ‘formally heretical’ and the second ‘at least erroneous in faith’ in theology.” By then, however, Copernicus’ mathematics had already been widely in use, and although many still viewed it as a hypothetical calculation model, it was unavoidable that questions about the nature of the cosmos as derived from the model would arise.

The scientific revolution had begun.