True, they must be, because it is impossible to know that which is not.
First, that is indemonstrable, because, if demonstrable, he cannot be said to know them who has no demonstration of them for knowing such things as are demonstrable is the same as having demonstration of them.
Causes they must be, and better known, and prior in time, causes, because we then know when we are acquainted with the cause, and prior, if causes, and known beforehand, not merely comprehended in idea but known to exist (The terms prior, and better known, bear two senses for prior by nature and prior relatively to ourselves are not the same, nor better known by nature, and better known to us I mean, by prior and better known relatively to ourselves, such things as are nearer to sensation, but abstractedly so such as are further Those are furthest which are most universal those nearest which are particulars, and these are mutually opposed.)
And by first, I mean principles akin to the conclusion, for principle means the same as first And the principle or first step in demonstration is a proposition incapable of syllogistic proof, i.e. one to which there is none prior. Now of such syllogistic principles I call that a θέσις which you cannot demonstrate, and which is unnecessary with a view to learning something else. That which is necessary in order to learn something else is an Axiom.
Further, since one is to believe and know the thing by having a syllogism of the kind called demonstration, and what constitutes it to be such is the nature of the premisses, it is necessary not merely to know before, but to know better than the conclusion, either all or at least some of, the principles, because that which is the cause of a quality inhering in something else always inheres itself more as the cause of our loving is itself more lovable. So, since the principles are the cause of our knowing and behoving we know and believe them more, because by reason of them we know also the conclusion following.