It has often been stated that the discoveries of quantum theory conflict with the philosophical premises underlying the pre-quantum scientific world-view; and yet, as Wolfgang Smith observes, it appears that the most basic philosophic premise behind that world-view has become ingrained in the scientific mentality to the point where it is no longer recognized as a philosophic assumption void of scientific support. Smith identifies this premise as the Cartesian subjectivization of the sensible or so-called secondary qualities, resulting in what Whitehead has termed "bifurcation." Basing himself upon his book The Quantum Enigma (Sugden, 1995), he shows not only that bifurcation can be jettisoned -- without in any way affecting the actual modus operandi of physics -- but that this step, in and by itself, eliminates the quantum paradoxes which have perplexed physicists since 1927, when the celebrated Bohr-Einstein debate first began. As Smith explains, non-bifurcation entails the distinction between two objective ontological domains: the corporeal, which we can perceive, and the physical, which we measure and observe by way of scientific instruments. Every corporeal object X, moreover, is associated with a corresponding physical object SX, from which it derives its quantitative attributes. And yet the two objects are altogether different, one can almost say: worlds apart. In the bifurcationist perspective, however, the two are implicitly identified. The prevailing scientific outlook is thus reductionist: it reduces the corporeal to the physical (the grey stone or red apple to an aggregate of molecules). And therein, according to Smith, lies the fundamental fallacy of the contemporaty world-view, which turns out also to be the source of quantum paradox. In the second part of the paper -- after pointing out that the Aristotelian / lThomistic philosophy is stringently non-bifurcationist -- Smith goes on to show that the results of physics, when interpreted on a non-bifurcationist basis, can be readily integrated into the Thomistic ontology, with the result that one is able to understand the nature and limitations of modern physics from a metaphysical point of view. In this perspective it becomes apparent that the factor distinguishing X from SX can be none other than the so-called substantial form of X, rejected by Galileo and Descartes. In light of these considerations, Smith concludes that the findings of quantum theory actually mandate a return to the pre- Cartesian ontology. The resultant rediscovery of "essence" -- beginning in the inorganic realm -- reverses the reductionism which for so long has dominated Western scientific thought, and opens the door to a deeper understanding of Nature.