An example of an historical alternative conception (being challenged):
"Those who hold that the heavens are filled with fluid matter, but suppose this matter to have no inertia, are saying that there is no vacuum but in fact are assuming there is one. For, since there is no way to distinguish a fluid matter of this sort from empty space, the whole argument comes down to the names of things and not their natures. But if anyone is so devoted to matter that he will in no way admit a space void of bodies, let us see where this will ultimately lead him.
For such people will say that this constitution of the universe as everywhere full, which is how they imagine it, has arisen from the will of God, so that a very subtle aether pervading and filling all things would be there to facilitate the operations of nature; this cannot be maintained, however since it has already been shown from the phenomena of comets that this aether has no efficacy."
Roger Cotes (1713) Editor's preface to the second edition, in Isaac Newton (1999) Mathematical Principles of Natural Philosophy (3rd edition, 1726): The authoritative translation (I. Bernard Cohen and Anne Whitman), University of California Press
