Problemata Aristotelis

he shows this in the Problems by the thing itself, and as if by pointing a finger, which in his other books—especially the Analytics—he taught in final words and universally. Therefore, this work collects, as far as the human mind can, the demonstration of natural and artificial things, so that the listener may achieve what the poet Maro Virgil sings: "Happy is he who has been able to know the causes of things." Since we took care to publish this most recent recognition and emendation of the Problems through the art of printing—in whose praise we said much in the preface to the works of John of Damascus 8th-century theologian printed in Venice—we have deservedly dedicated it to you, Sixtus IV, supreme pontiff, under whose reign it was done, so that it may come into the light under the best auspices. If it should be dedicated to you, of all Christian princes, as the greatest and most religious, and as a most grave philosopher, it is dedicated to the work of Aristotle, the prince of philosophers.

THE FIRST PART OF THE PROBLEMS OF ARISTOTLE THE PHILOSOPHER, INTERPRETED BY THEODORUS THROUGH THE FINAL EMENDATION

Why do the excesses of something have the power to cause illnesses? Is it because they effect either an excess or a defect, in which it is certain that disease consists?
Why can diseases often be cured where one has exceeded in abundance? Indeed, some physicians practice this art, so that they act only through excess, whether of wine, or water, or salt, or food, or fasting. Is it because the causes that bring about diseases are adverse to one another, and thus it is brought about that one genus can be brought into the middle through the excess of another?