## Ars Brevis

### The Fourth Figure

4. The Fourth Figure

The fourth figure has three circles. The outer one is immobile, whereas the two inner ones are mobile, as shown in the figure.

Turn the middle circle inside the outer circle to place C under B. Then turn the inner circle inside the middle circle and place D under C. This gives rise to nine cameras: first BCD, then CDE, and so forth.

Next, by placing E of the inner circle under C of the middle circle you form nine other cameras: first BCE, then CDF etc. And while all the letters of the inner circle combine in sequence with B of the outer circle and C of the middle circle, C is the medium between B and D because B and D participate with each other through the things signified by C. This applies to all the cameras. By going through the cameras in this way, you can track down the conclusions you need.

Next, combine the letters with B in the outer circle and D in the middle circle followed by the other letters of the middle circle and the inner circle, moved in sequence, while B of the outer circle remains immobile, until I of the middle circle and K of the inner circle arrive under B of the outer circle, producing 252 cameras in the process.

This figure is more general than the third because each camera of this figure has three letters, whereas the third figure only has two letters par camera. This is why the intellect is more general with the fourth figure than with the third.

The fourth figure has this condition: that the intellect apply to the subject at hand the letters which seem most applicable to this subject. Once a camera is made with three letters, the intellect considers the meanings of the letters and ensures agreement between the subject and the predicate while avoiding disagreement. This condition enables the intellect to use the fourth figure to build science and to bring many reasons to bear on the same conclusion.

We have dealt with the four figures, and they must be known by heart, without which the artist cannot make any good practical use of this Art.