The medieval background to Copernicus, an essay originally published in the book Copernicus Yesterday and Today and subsequently published in the book Stars, Minds, and Fate, seeks to make two points. The first point is to dismiss any notion that planetary astronomy was alien to medieval European astronomy, and the second point is to show that Copernicus has an allegience with medieval astronomy through an implicit unity of the cosmos.
The second point interests me more in that a certain cosmological unity was present from Aristotle to the Middle Ages to Copernicus, even though the contemporary cosmology was disintegrating by the time of Copernicus.
Aristotelian cosmology maintained that everything had its proper place in the cosmos. Copernicus even generalized Aristotle in explaining gravity as a "natural striving implanted in the parts by the divine providence of the maker of all things, so that they may come together in the form of a globe, in unity and wholeness". This passage is the strongest point presented in the essay in establishing the Medieval Background to Copernicus, even though Aristotelian cosmology was superceded by a Ptolemaic scheme.
The Ptolemaic scheme enjoyed great influence as it integrated astrology with Aristotle. Medieval astronomy developed an integrated planetary system based on the contemporary Ptolemaic scheme, and never lost the mark of Aristotle's cosmology; everything has its place in an ordered whole. The harmonious overall scheme is the most striking characteristic to have influenced Copernicus. A central tenant of Copernican astronomy is the assumption that everything would move uniformly about its proper center, even if the center was no longer the Earth as was assumed in Medieval astronomy.
It should be noted as well that from an ontological standpoint faith was more real than physics in Medieval cosmology and astronomy was perhaps the least real.