In De revolutionibus Copernicus states several reasons why it is logical that the sun would be at the centre of the universe:-
At the middle of all things lies the sun. As the location of this luminary in the cosmos, that most beautiful temple, would there be any other place or any better place than the centre, from which it can light up everything at the same time? Hence the sun is not inappropriately called by some the lamp of the universe, by others its mind, and by others its ruler.
Copernicus's cosmology placed a motionless sun not at the centre of the universe, but close to the centre, and also involved giving several distinct motions to the Earth. The problem that Copernicus faced was that he assumed all motion was circular so, like Ptolemy, was forced into using epicycles (see for example ). It was consequently considered implausible by the most of his contemporaries, and by most astronomers and natural philosophers until the middle of the seventeenth century. In the intended Preface of De revolutionibus orbium coelestium Copernicus showed that he was fully aware of the criticisms that his work would attract:-
Perhaps there will be babblers who, although completely ignorant of mathematics, nevertheless take it upon themselves to pass judgement on mathematical questions and, badly distorting some passages of Scripture to their purpose, will dare find fault with my undertaking and censure it. I disregard them even to the extent as despising their criticism as unfounded.
Its notable defenders included Kepler and Galileo while theoretical evidence for the Copernican theory was provided by Newton's theory of universal gravitation around 150 years later.
Copernicus is said to have received a copy of the printed book, consisting of about 200 pages written in Latin, for the first time on his deathbed. He died of a cerebral haemorrhage.
Brahe, who did not accept Copernicus's claim that the Earth moved round the sun, nevertheless wrote:-
Through observations made by himself [Copernicus] discovered certain gaps in Ptolemy, and he concluded that the hypotheses established by Ptolemy admit something unsuitable in violation of the axioms of mathematics. Moreover, he found the Alfonsine computations in disagreement with the motions of the heavens. Therefore, with wonderful intellectual acumen he established different hypotheses. He restored the science of the heavenly motions in such a way that nobody before him had a more accurate knowledge of the movements of the heavenly bodies.
Rudnicki gives this appreciation of Copernicus:-
He was truly creative. His scientific method, though determined by the horizons of contemporary knowledge and belief, was yet ideally objective. Ethically, his actions throughout his life bear witness to the highest standards. He did good. He earned the general respect and honour of his contemporaries. For many years he served self-sacrificingly the cause of his native country. But he knew no private, domestic joys.
J J O'Connor and E F Robertson