Hence we perceive not only that the human mind is united to the body, but also what is to be understood by the union of mind and body. But no one can adequately comprehend it without previously possessing adequate knowledge of the body. In proportion as one body is better adapted than another to act or suffer, the mind will at the same time be better adapted for perception. And the more independent a body may be of other bodies, the stronger will be the understanding of the mind. Thus we can determine the superiority of one mind over another.
All bodies are either moving or resting. Every body moves sometimes slowly, sometimes quickly. Bodies are distinguished from each other by degrees of motion and quiescence, not with regard to substance. All bodies agree in some aspects. Bodies affect each other in motion and rest. Each individual thing must necessarily be determined as to motion or rest by some other thing.
The human body needs for its preservation many other bodies by which it is, as it were, regenerated. The human mind increases its aptitude in proportion to the number of ways in which the body can be disposed. The idea constituting a formal being of the human mind is not simple, but is highly complex. An idea of each component part of the body must necessarily exist in God.
The human mind does not know the human body itself, nor does it know that the human body exists, except through the ideas and affections by which the body is affected. Indeed, the human mind is the very idea or knowledge of the human body. These ideas are in God. Thought is an attribute of God, and so the thought of the mind originates of necessity in Him. All the ideas which are in God always agree with those things of which they are ideas, and therefore they are all true.
Falsity consists in privation of knowledge, involved in confusion and mutilation of ideas. For instance, because they think themselves to be free, and the sole reason for this opinion is that they are conscious of their own actions, and ignorant of the causes determining those actions. Nobody knows what the will is and how it moves to-day. Those who pretend otherwise and invent locations of the soul, usually excite derision and disgust.
When we look at the sun and imagine it to be immensely nearer to us than it really is, the error arises from the manner in which the essence of the sun affects the body, not merely from the exercise of the imagination.
Mutual Influences
The more things the body possesses in common with other bodies, the more things will the mind be adapted to perceive. The human mind possesses an adequate knowledge of the eternal and infinite essence of God. But the reason why men have not a knowledge of God as clear as that which they have of common notions is that they cannot imagine God as they can imagine bodies, and because they have attached the name of God to the images of things they are accustomed to see. This they can hardly avoid, because they are constantly affected by external bodies. And, indeed most errors arise from our application to the wrong names of things.
For if some one says that the lines drawn from the centre to the circumference of a circle are unequal, it is because he understands by a circle something different from what we understand by the mathematicians. I did not reckon a man to be in error whom I recently heard complaining that his court has flown into one of his neighbour's fowls for I understand what he meant.
In the mind there is no absolutely free will. The mind is determined to this or that volition by a cause, which is determined by another cause, and so on ad infinitum. The will and intellect are one and the same. We are partakers of the divine nature in proportion as we more and more understand God and conform our actions to his will. Our highest happiness consists in this conformity, by which alone the soul finds repose. Those greatly err from the true estimate of virtue who expect to be rewarded for it, as though virtue and the service of God were our felicity itself and the highest liberty.