Early modern philosophers often subscribe to the substance theory, which suggests that of all things there must be a source. This source must be able to exist without dependence on another entity. This source is God.
In determining the origin of life and all that exists in the world, many religions and philosophies subscribe to the substance theory, which poses that a substance is the most fundamental base or object. Such an absolute and underlying substance is God, as it is in-and-of itself a conclusive and absolute being. God has no reliance on other forms of existence in order to operate, so God is the underlying substance beneath all forms of life. Descartes reasons that God is the only true substance, as it is able to exist in such a way that it does not rely on other forms or objects to exist. This belief subscribes to Cartesian dualism.
In extension to things that derive from creation, we can come into existence because of God’s will. Any entity that is all powerful or able to determine the outcome to all events must be the causation, therefore God is what eventuates the existence of all things. God and nature are interchangeable concepts, as we believe all things to take place through the course of nature. As such, the laws of nature are the laws willed by God.
Hume’s bundle theory refutes the theory of substance. It posits that anything and everything is a collection of different properties aligned together and consist of nothing more than those properties. An entity does not exist without the characteristics that make it so. Without those characteristics, there is nothing. Hume argues that there is no such thing as a foundational substance; without properties that make something what it is, it simply is nothing.