Matters that one actually witnesses are, for those who have learned of them through mass-transmitted reports, classed among the mutawātir certainties. Others, however, may know of them only by way of a lone or conjectural report, so for them they fall under what is merely probable; and if they have never heard of them at all, such matters remain, for them, in the realm of the unknown. The same holds true for purely rational truths: people differ in their power of perception to a degree whose two extremes can scarcely be measured, so that what is self-evident and necessary knowledge for one person another may deny outright or at least doubt. This is plain both in the sphere of conceptions and of propositions.

Because all of this is relative, a conception may be self-evident to some people while not being so to others; those for whom it is intuitive need no definition—and this is exactly what we observe in practice. Should someone object, “Then whoever fails to grasp those delimited ideas by intuition will attain them through a definition,” we answer: many treat this as a universal rule that applies to every theoretical issue and to all people alike, and that is a manifest error. Anyone who reflects on what we have set forth will realize that the person who does not yet know a thing intuitively can come to know it intuitively through the same means by which others attained it; hence it is impermissible to claim that he can learn it only through formal definitions.