Book One.

The text begins mid-sentence, concluding the thought from the previous page regarding definitions. ...perfect [knowledge] of such things: it is necessary to recur to that instrument, which is used by every Science, called Demonstration: which is that which truly makes us know. 1. Aristotle, Posterior Analytics, Book 2. It is very true that not all Sciences use the same means: because there being Four causes—as I declared in the Institutions—not all demonstrate through all four mentioned: 1. Zarlino, Istitutioni, Part 1, Chapter 41. since Metaphysics demonstrates only through the formal and final causes, and also through the efficient; Natural Science In the 16th century, "Natural Science" or "Physics" referred to the study of the physical world and its changes. demonstrates through every cause; but the Mathematician (leaving some other opinion aside) demonstrates only through the formal cause.

ADRI. By the formal causes, then, you will have to demonstrate the things of Music to us.

GIOS. So it will be, insofar as it is Mathematics: however, when it had to be demonstrated as Natural Science—since Music is placed between these two genres—one would proceed otherwise. But before we pass to demonstrating anything: it will be well done for some of you, who are not so well practiced in the study of letters, to go about remembering (as I have said again) what Demonstration is: and to show its conditions: and how its premises, or propositions, of which it is composed, must be.

DESI. It will be well done indeed: so as not to have to declare them out of season.

CLAV. This is exactly what I wanted to tell you: although I have a little practice in it: because many times I have (as I also said) heard it discussed.

ADRI. Truly the knowledge of these things is necessary: because not understanding them, one does not have that enjoyment and that delight: nor does one draw from it that utility which would be needed. But I believe that I will remember everything as you go along commemorating them.

DESI. You were in Paris, Master Adriano, according to what you have already said.

ADRI. I was: and I began to study: but God has willed that I teach Music in the end.

GIOS. Master God original: "Messer Domenedio" knew very well that the world had need of a man like you; therefore he gave us you, so that you might illuminate those who delight in this so noble Art: and I will also say this Science. For if it had not been for you, I would not have set myself to see so intrinsically, as I have done, and so minutely, the things of Music. But I would have relied, as many have done, on the judgment of others: and I would have held to what I had found written by other writers: believing them and persuading myself that it was as they had written. Therefore it was well done that you left the study of Laws, and attended to Music: since in this you now hold the first place: and God knows—though you are not without judgment—if in that profession you would have held the third.

ADRI. Thus it has pleased God: and I am content with it.

FRAN. You can be content with it, Master. But let us put these things aside: because time passes: and we have not yet begun to discuss what has been proposed.

GIOS. Know then—so that I may follow what I had begun—that Demonstration is properly like an instrument that leads us to Knowledge, and to the acquisition of Science: and this is its true end, to which we tend. But take note, that here by Knowledge original: "Sapere" I mean nothing other than knowing things by means of their true and proper causes: in such a way that it is clearly understood that they could not be, nor could they stand otherwise than how they are known. And this, I say, is true Knowledge, and true Science.

Know, however, that Knowledge is found to be of two kinds: the first is called Knowledge in itself original: "Sapere per sè." In logic, this refers to knowledge derived from the essential nature of a thing.: and the other Knowledge by accident original: "Sapere per accidente." This refers to knowledge of a thing through its non-essential or incidental qualities.. The first is that when we know the conclusion by means of the propositions, or premises, which are of themselves essential.

FRAN. Bring back to my memory what you mean by these propositions, or premises, which are of themselves essential.

GIOS. I will do it step by step.

ADRI. Give us also an example of what you have said.

GIOS. I am happy to: but do not be in a hurry. I say that the first way is when one knows Man to be risible In traditional logic, "risible" means the capacity to laugh. This was considered a property unique to humans, making it a classic example of an essential attribute., by means of this greater proposition: when I say: the rational animal is risible: and by means of this minor proposition: Man is a rational animal: from this I draw the conclusion, and I say: Therefore Man is risible.

ADRI. This then is Knowledge in itself: from what I perceive.

GIOS. That is how it stands.

ADRI. Follow with Knowledge by accident.

GIOS. Knowledge by accident (to declare to you the second way) is knowing the thing by means of premises that are accidental.

CLA. Give us the example, please.

GIOS. Just as if I wanted to prove that Man composes: I would say. The Musician composes: Man is a Musician: therefore Man composes: and this would be Knowledge...