 According to Vives, things have two different layers: one external, consisting in the sensible accidents of the thing, and another, internal, and therefore hidden, which is the essence of the thing (III, 197). “The true and genuine essences of all things”, he writes, “are not known by us in themselves. They hide concealed in the innermost part of each thing where our mind, enclosed by the bulk of the body and the darkness of life, cannot penetrate” (III, 406–7). Vives subscribes to the Aristotelian principle that all of our knowledge has its origin in perception. We cannot learn anything, he maintains, except through the senses (III, 193 and 378). But he also maintains that the human mind “must realize that, since it is locked up in a dark prison and surrounded by obscurity, it is prevented from understanding many things and cannot clearly observe or know what it wants: neither the concealed essence of material things, nor the quality and character of immaterial things; nor can it, on account of the gloom of the body, use its acuity and swiftness” (III, 329). In other words, since the senses cannot grasp what is incorporeal or hidden, sense perception does not yield any knowledge of the essence of things but only of their accidents. Vives’ view, however, is that sensory knowledge must nonetheless be transcended by means of reasoning. Yet, according to him, the best that human reason can accomplish in this process is to provide a judgment grounded in all the available evidence, thereby increasing the probability of the conclusion. In his view, our knowledge of the essence of a thing is only an approximate guess based on the sensible operations of the thing in question (III, 122).