Medicine examines the human body as it is healthy or deteriorating. Knowledge of any thing, if it arises, is achieved and becomes perfect through knowledge of its causes, if they exist Therefore, in medicine one should know the causes of health and disease. These reasons can be obvious, but they can also be hidden, comprehended not by feeling, but by inference based on accidents Therefore, in medicine it is also necessary to know the accidents that occur in health and illness. In the true sciences it is explained that knowledge of a thing is acquired through knowledge of its causes and principles, if they are inherent in it, and if they are not, then through knowledge of its accidents and obligatory essential features.
Causes, however, are of four varieties - material, efficient, formal and final. Material causes are the foundations in the body in which health and disease exist. The nearest basis is the organ or pneuma, the more distant basis is the juices, and the even more distant are the elements. These last two bases differ depending on the combination, although with the combination a transformation also takes place. Everything that is arranged in this way tends, when combined and transformed, to some kind of unity in this situation, the unity associated with this multiplicity is either nature or a specific form. As for nature, it arises by transformation, while a certain form arises by combination.
Efficient causes are causes that change the state of a person's body or keep it unchanged. These are the states of the air and the things connected with them food, water, drinks and things related to them evacuation, constipation, country, home and what is connected with it, bodily and mental movements and peace. These same reasons include sleep, wakefulness, the transition from one age to another, differences in age, sex, craft, habits, as well as what happens to the human body and comes into contact with it - either not contrary to nature, or contrary to nature. nature.
Formal causes are natures and forces arising after them, as well as combinations.
As for final causes, these are actions. The knowledge of actions inevitably includes the knowledge of forces, as well as the knowledge of pneuma, the supporting force, as we will explain later.
This is the content of medical science, since it studies the human body - how it is healthy and how it is sick. However, from the point of view of the ultimate goal of this research, that is, the preservation of health and the cessation of disease, medicine must also have other subjects according to the means and instruments used in these two conditions. The means here are the appropriate use of food and drinks, the correct choice of air, determining the measure of rest and movement, treatment with medicines and treatment with the hand. Doctors apply all this in accordance with three types of people: healthy, sick and average we will talk about average people later and say why they can be considered to stand between two groups that are in fact not connected by any intermediate link.
And now, when we have given these explanations separately, collectively we have it that medicine examines the elements, natures, juices, simple and complex organs, pneumas with their natural, animal and mental forces, actions and states of the body - health, illness and the average state, as well as the causes of these states: foods, drinks, air, water, country, home, evacuation, constipation, craft, habits, movements and rest of the body and soul, age, sex, those unusual events that happen to the body, a reasonable regime in food and drink, the choice of suitable air, the choice of movement and rest, as well as treatment with medicines and manual actions leading to the preservation of health, and treatment of each disease separately.
Some of these things the doctor should, since he is a doctor, imagine only essentially, scientifically, and confirm their existence by the fact that these are generally recognized things, accepted by experts in the science of nature others he is obliged to prove in his art. Speaking about those of them that are similar to axioms, the doctor must affirm their existence unconditionally, for the principles of the particular sciences are indisputable and they are proven and explained in other sciences that stand ahead of them So it goes further and further until the beginnings of all sciences rise to the first wisdom, which is called the science of metaphysics. When someone who claims to be a doctor begins and begins to reason, proving the existence of elements, natures and what follows them and is the subject of the science of nature, he makes a mistake, since he introduces into the art of medicine something that does not belong to the art medicine. He is also mistaken in that he believes that he has explained something like this, when he did not explain it at all.
Things that a doctor must imagine only in essence, unconditionally affirming the existence of those of them whose existence is not obvious, come down to the following totality: that the elements exist and there are so many of them that natures exist, there are so many of them and they represent such and such that juices also exist, are such and such, and there are so many of them that pneumas exist, there are so many of them and they are located there that change and immutability always have a cause that there are so many reasons. And the doctor must understand the organs and their useful functions with the help of external senses and anatomy.
As for those things that a doctor is obliged to both imagine and prove, these are diseases, their particular causes, their symptoms, as well as how to stop the disease and maintain health. The doctor is obliged to give evidence of the existence of those of these things that exist hidden, in all detail, indicating their magnitude and frequency.
Galen, when he tried to substantiate the first part of medicine with logical evidence, preferred to approach this not from the point of view of a doctor, but from the point of view of a philosopher talking about natural science. In the same way, a lawyer, trying to justify why it is necessary to follow the unanimous decision of authorities, can do this not as a lawyer, but as a theologian. However, if the doctor, because he is a doctor, and the lawyer, because he is a lawyer, are not able to decisively prove their positions, then a vicious circle will result.