for when the one loses its leaves and fades away, then the other begins to shoot, and blossom, and look green, so that one might fancy that the one withered through dissatisfaction at the blooming appearance of the other.
It is with reference to this that Moses represents in a most natural manner the departure of Jacob to be contemporaneous with the arrival of Esau; "For it came to pass," says he, "that as Jacob went out his brother Esau came in." Genesis xxvii. 30. As long, indeed, as prudence dwells in and makes his abode in the soul, so long every companion of folly is discarded and banished to a distance; but when prudence departs then folly rejoices and enters, since its enemy and adversary, for whose sake it was driven away and banished, is no longer inhabiting the same place as before.
 We have now then said enough by way of preface to this treatise. We will proceed to adduce the proofs of
 Genesis xxvii. 30. 
 
all that we have said, beginning first of all to establish the first point.
We said, then, that ignorance was the cause of man’s behaving foolishly and misconducting himself, just as a great quantity of unmixed wine is to great numbers of foolish persons; for ignorance is the primary evil of all the errors of the soul, if we must tell the truth, from which, as from a spring, all the actions of life do flow, never producing to any one, one single stream of wholesome or drinkable water, but only brackish water, the cause of disease and destruction to all who use it.