The notion of matter had been invariably used in philosophical discussions from the High Middle Ages down to early modern times. In this long history of its usage, however, one cannot fail to notice a rather radical semantic shift. What was originally the relational notion of the Peripatetic ὕλη, or Thomist materialitas, which was reserved for the proximate substrate of enmattered phenomena [λόγοι ἔνυλοί], gave way to the absolute notion for the totality of the world as external [res extra me posita], to the point where questioning the existence of matter became equivalent to a skepticism in regards to the existence of a mind-independent world tout court. The following study presents three key moments in this tumultuous historical development of matter, from being a constitutive part of things, to becoming a thing in itself, to be finally reduced to nothing. Accordingly, the arc of this story begins with the popular Renaissance understanding of ὕλη rooted as it was in Aquinas and Averroës and expounded by Alessandro Piccolomini (Chapters I-II); it then segues into the Cartesian matter posited besides the thinking substance (Chapter III); and closes with George Berkeley declaring matter an empty and even contradictory notion (Chapter IV). This developmental story suggests that each thinker, in deciding which aspects of experience he was going to be realist about, was inevitably influenced by the specific theoepistemic values he was operating within. It will become clear that each iteration in this gradual vanishing of matter was embedded in larger œconomies of ideas, axioms, and intuitions each of which came with their proper metaphysical anthropology; the boundaries drawn between mind and matter, self and world; and, ultimately, the degree to which material things could be known at all. Aquinas felt compelled for conceptual as well as doctrinal reasons to make the human mind rely on an external material world for both its world-directed and reflexive functions. Though always turned to (convertendo ad) the world of particulars as the proper and immediate object of the intellectus, however, the postlapsarian man could never know a subsistent thing by its essence, including his own self, at least not in vita præsentia. But when we reach Descartes, we find him thinking in terms of the new values emerging in his day: the historical urgency for a rational demonstration of the immortality of the soul; new perceived ways divine benevolence can be cashed out; and the ambient epistemic optimism about finding certainty in nature. Descartes will raise the thinking self to a first principle of knowledge, and the like level of intuitive certainty afforded introspectively he will raise it to a first principle of being: conceivability becoming the true mark of existence, actual or potential. To make this cogito metaphysically possible, however, Descartes had to reconfigure the traditional distinctions between mind-thought, self-world. So the reader of the Meditationes (1641) is asked to relinquish a mindset that had taken the existence of the external world as intuitively evident, but left the immortality of the soul be settled by revelation, and enter another where the self could identify itself with its immortal cogitative part but which leaves the existence of anything outside of it uncertain or inconclusive. Consequently, the existence of matter that was admitted as an indemonstrable postulate in premodern times (Ch. I-II), would stand as a demonstrable theorem in the modern (Ch. III.IV). Ultimately, this seemed to have set off a process of dematerialization or spiritualization of the world that would not be completed until all ideas had been purged of their material counterpart in the real world, culminating in the first modern immaterialist (or absolute idealist) view arrived at independently by George Berkeley (1710, 1713) and Arthur Collier (1713). In his time, Berkeley (Chapter IV) found that original notion of a material substratum to have receded further away from our grasp, towards the vanishing point of any possible characterization. Confronted with such featurelessness, Berkeley urges the doctrine of matter be dropped entirely in the name of an all inclusive mode of existence in two voces: thinking and being thought, percipere et percipi.