developed a scheme of categories different from Aristotle's based on the ideas of Anaxagoras and Timaeus. The fundamental basis of Stoicism in this context was a universally consistent ethical and moral code that should be maintained at all time, the physical belief of beings as matter is an important philosophical footnote, as it marked the start of thinking as beings as inherently linked to reality, instead of to some abstract heaven. Neoplatonism Neoplatonists argue that beneath the surface phenomena that present themselves to our senses are three higher spiritual principles or hypostases, each one more sublime than the preceding. For Plotinus, these are the soul or world-soul, being/intellect or divine mind (nous), and "the one". Early modern philosophy René Descartes means by a substance an entity which exists in such a way that it needs no other entity in order to exist. Therefore, only God is a substance in this strict sense. However, he extends the term to created things, which need only the concurrence of God to exist. He maintained that two of these are mind and body, each being distinct from the other in their attributes and therefore in their essence, and neither needing the other in order to exist. This is Descartes' substance dualism. Baruch Spinoza denied Descartes' "real distinction" between mind and matter. Substance, according to Spinoza, is one and indivisible, but has multiple "attributes". He regards an attribute, though, as "what we conceive as constituting the [single] essence of substance". The single essence of one substance can be conceived of as material and also, consistently, as mental. What is ordinarily called the natural world, together with all the individuals in it, is immanent in God: hence his famous phrase deus sive natura ("God or Nature"). John Locke views substance through a corpuscularian lens where it exhibits two types of qualities which both stem from a source. He believes that humans are born tabula rasa or “blank slate” – without innate knowledge. In An Essay Concerning Human Understanding Locke writes that “first essence may be taken for the very being of anything, whereby it is, what it is.” If humans are born without any knowledge, the way to receive knowledge is through perception of a certain object. But, according to Locke, an object exists in its primary qualities, no matter whether the human perceives it or not; it just exists. For example, an apple has qualities