We should observe what is most simple

To distinguish the simplest things from the involved and to pursue them in order, it is necessary in each series of things, in which we have directly deduced several truths from one another, to observe what is most simple, and how from this all other things are more or less or equally removed.

Although this proposition may not seem to teach anything very new, it contains the chief secret of the art, and is no less useful in this whole Treatise: for it advises that all things can be arranged in certain series, not indeed as they are referred to any genus of being, as those philosophers have divided them into their categories, but insofar as they can be known from one another, so that whenever a difficulty arises, we can immediately observe whether it will be profitable to explore some others first, and which ones, and in what order.

But so that this can be done correctly, it must be noted first that all things, in the sense in which they can be useful for our purpose, where we do not consider their solitary natures but compare them among themselves, so that they may be known from one another, can be said to be either absolute or relative.

I call absolute whatever contains within itself a pure and simple nature, about which the question is: such as everything that is considered as if independent, cause, simple, universal, one, equal, similar, straight, or other such things; and I call the first of these also the simplest and easiest, so that we use it in resolving questions.

Relative, however, is what either has the same nature, or at least something of it, insofar as it can be referred to the absolute and deduced by a certain series from it; but in addition, it involves certain other things in its concept, which I call relations: such is whatever is called dependent, effect, composite, particular, many, unequal, dissimilar, oblique, etc. Which relations are removed from the absolute, the more subordinated relations they contain among themselves; which all should be distinguished in this rule, and their mutual natural connection and order must be observed so that we can proceed from the last to that which is most absolute by passing through all others.

And in this consists the whole secret of the art, that we carefully observe the most absolute in all things. For some things under one consideration are more absolute than others, but seen differently are more relative: as the universal is more absolute than the particular, because it has a simpler nature, but it can also be called more relative, because it depends on individuals to exist, etc.

Also sometimes things are truly more absolute than others, but not yet the most of all: as if we look at individuals, the species is something absolute; if the genus, it is something relative; among measurable things, extension is something absolute, but among extensions, length, etc. Also finally, to understand better here the series of things to be known, we do not ignore the nature of each, as the purpose of retaining them, but rather distinguishing them from the nature of each.