Francis Bacon’s theory of matter is a controversial topic among historians. I agree with the viewpoint, which suggests that although Bacon changed his views on atomism repeatedly, he never rejected it completely (Partington, Urbach, Gemelli). I will substantiate this interpretation by paying more attention to the usually neglected allegorical works and by investigating why Bacon changed his mind on atomism in his Novum organum. I shall reconstruct Bacon’s various opinions in chronological order to establish his final evaluation of atomism and (...) his reasons for it. Given that Bacon never embraced a matter theory identical with Greek atomism, I shall here define atomism in the broadest sense, as a corpuscular matter theory that posits final and indivisible particles. Following this semantic delimitation, two successive Baconian opinions will be distinguished: the first took the atom to constitute an ontological and causative-operational principle; the second deprived the atom of this causative-operational ability, but did not touch its ontological priority. At the same time, I will investigate the question concerning the coexistence of atomism and pneumatism in Bacon’s theory, a point that has been discussed in the influential interpretations by Kargon and Rees. I shall argue that Bacon did not regard these two doctrines as incompatible. (shrink)