SECTION EIGHT

THE FIRST DIVISION OF THE BRANCHES
OF KNOWLEDGE

CHAPTER 2

On the two ways: observation and reasoning

1466. The principle of method that we have previously considered as a way of ordering all human knowledge may be stated as follows: 'State first that which, in order to be understood or demonstrated, has no need of subsequent teaching.' This does, however, offer some difficulty to thought. It is easy to say that the final proposition must be demonstrated by means of the penultimate, the penultimate by means of its predecessor, and so on back to the first proposition. But how do I then demonstrate the first proposition? And if I do not demonstrate it, do I not take for granted, and consequently find useless, the demonstrations dependent upon this first proposition?

This kind of reasoning supposes something which is not the case, that is, that every proposition must be demonstrated by its preceding proposition. But we need to consider, on the contrary, that the nature of the first proposition is such that it includes proof of itself within itself. In other words, it is evident and unassailable, it is what is true per se because it is truth itself.

1467. But where do we discover this principle, and how do we discern it from all the others? We find it in ourselves because it is always present to us; we have no need to look for it by means of reasoning, but to observe it as something that we intuit naturally. The sceptic himself will see it, and conceive it reflectively, provided interiorly he turns his thought to himself. Turning the gaze of his mind on his cognitions, he will see the idea of being in them. If he concentrates his attention ever more carefully upon it, contemplating and analysing it while noting its essential characteristics, he will find himself unable not to perceive its light, necessity, evidence and immutability. All learned human knowledge begins with this observation, not with any other means. For the sceptic, too, observation is the first step on the return to the right path.

The first branch of knowledge therefore is knowledge from observation, not reasoning. This enables us to avoid the vicious circle so easy to enter when setting out the divisions of the branches of knowledge. In other words, demonstration terminates in observation which, as the intellection of truth known per se, is the fount of all demonstrations.