For the soul flourishes for the pursuit of knowledge when the prime vigour of the body is withering away from the lapse of time; therefore, before one has arrived at one’s prime and vigour by reason of a more accurate comprehension of things, it is not difficult to be tripped up. But this accident is common to all people who are fond of learning, to whom new subjects of contemplation are continually rising up and striving after old ones, the soul itself producing many such subjects when it is not barren and unproductive. And nature, also, unexpectedly and spontaneously displaying a great number to those who are gifted with acute and penetrating intellects. Therefore the well of knowledge is shown to be of this kind, having no boundary and no end.
 We must now explain why it was called the well of the oath. Those matters which are doubted about are decided by an oath, and those which are uncertain are confirmed in the same manner, and so, too, those which want certification receive it; from which facts this inference is drawn, that
 
there is no subject respecting which any one can make an affirmation with greater certainty than he can respecting the fact that the race of wisdom is without limitation and without end. It is well, therefore, to enrol one’s self under the banners of one who discusses these matters without an oath; but he who is not very much inclined to assent to the assertions of another will at least assent to them when he has made oath to their correctness. But let no one refuse to take an oath of this kind, well knowing that he will have his name inscribed on pillars among those who are faithful to their oaths.
 However, enough of this. The next thing must be to consider why it is that as four wells had been dug by the servants of Abraham and Isaac, the fourth and last was called the well of the oath. May it not be that the sacred historian here desires to represent, in a figurative manner, that as in the universe there are four elements of which this world is composed, and as there are an equal number in ourselves, of which we have been fashioned before we were moulded into our human shape, three of them are capable of being comprehended somehow or other, but the fourth is unintelligible to all who come forward as judges of it.