parallelism is called occasionalism. Defended by Nicolas Malebranche (1638–1715), occasionalism agrees that mind and body are separated but does not agree with Descartes's explanation of how the two interact. For Malebranche, God intercedes if there was a need for the mind and body to interact. For example, if the body is injured, God is aware of the injury and makes the mind, or the person (subject of experience), feel pain. Likewise, if a person wants to move their hand, i.e. to grasp an object with their fingers, that want is made aware to God and then God makes the person's hand move. In reality, the mind and body are not actually in contact with each other, it just seems that way because God is intervening. Occasionalism can be considered as parallelism with divine intervention, because if God did not mediate between the mind and body, there would not be any interaction between the two. Spinoza According to Baruch Spinoza, as mentioned in his publication Ethics, the two attributes of God, namely thought and extension, are not related causally. Rather, they are two different means of comprehending one and the same reality. Thus, the human body has a corresponding idea, which is the human mind or soul. Whatever happens in the body always occurs in tandem with contents of the mind. Since everything that exists is a modus of God, Spinoza's concept represents a monist account of parallelism, contrary to Leibniz's pluralist version. Leibniz German philosopher Gottfried Wilhelm Leibniz concluded that the world was composed of an infinite number of life units called monads (from the Greek monas, meaning "single"). Similar to living atoms, monads are all active and functioning. As there is naturally a hierarchy in nature, monads vary in degrees of intelligence. Some are more specialized and are more capable of having more distinctive thoughts, opposed to monads that are simpler in structure. Next to God, humans possess the monads that are able to exhibit the most complex type of comprehensive thinking. However, humans possess many types of monads, varying from very simple to very complex forms, which explains why the ideas we experience at times differ in clarity. Monads according to Leibniz can never be influenced by anything outside of themselves. Therefore, the only way that they can change is by internal development, or more specifically, by actualizing their potential. He believed monads never influence each other; it