The sum of the matter is that God necessarily exists; that He is one God; that He acts from the necessity of His nature; that He is the free cause of all things; that all things depend on Him; and that all things have been predestined by Him.
II.—Concerning Mind
I pass on to those things which must necessarily follow from the essence of the eternal and infinite God.
Thought is the attribute of God. Individual thoughts are modes expressing the nature of God in a certain and determinate manner. The order and connection of these ideas coincides with the order and connection of things, therefore God's power of thinking is equal to His power of acting. The circle existing in nature and the idea of an existing circle which is also in God, are one and the same thing, exhibited through different attributes. God is truly the cause of things as they are in themselves, in so far as He consists of infinite attributes.
The first thing which forms the actual Being of the human mind is nothing else than the idea of an individual actually existing. The essence of man is formed by certain modes of the Divine attributes, that is to say, modes of thought. The idea is the first thing which forms the Being of the human mind. It must be an idea of an individual thing actually existing. Hence the human mind is part of the infinite intellect of God.
The knowledge of everything which happens necessarily exists in God, in so far as He forms the nature of the human mind. Man thinks. Modes of thought, such as love, desire, or affections of the mind under whatever designation, do not exist, unless in the same individual exists an idea of a thing loved, desired, etc. But the idea may exist though no other mode of thinking exists. Therefore the essence of man does not necessarily involve existence.
We perceive that a body is affected in certain ways. No individual things are felt or perceived by us except bodies and modes of thought.
The object of the idea constituting the human mind is a body, or a certain mode of actually existing extension, and nothing else. For if the body were not the object of the human mind, the ideas of the affections of the body would not be in God, in so far as He has created our mind, but would be in Him in so far as He has formed the mind of another thing.
But we have ideas of the affections of the body; therefore the object of the idea constituting the human mind is the body actually existing. It follows that man consists of mind and body, and that the human body exists as we perceive it.
Mind and Body