_Of the Mutual Relation between Ignorance and Vice, and Knowledge and Purity._ [Sidenote: Part I. page 22, _&c._] What are Ignorance and Vice but Diseases of the Mind contracted in its two principal Faculties the Understanding and Will? And such too as like many Bodily distempers do mutually foment each other. Ignorance disposes to Vice, and Wickedness reciprocally keeps us Ignorant, so that we cannot be free from the one unless we cure the other; the former part of this Proposition has been already shewn, and the latter may easily be made apparent; for as every Plant does Naturally draw such juices towards it as serve for its Nutrition, as every Creature has an aptness to take such courses as tend to its preservation; so Vice that spawn of the Devil, that _Ignis fatuus_ which can’t subsist but in the dark night of Ignorance, casts forth Vapours and Mists to darken the Soul and eclipse the clear light of Knowledge from her View. And tho a Wicked Man may pretend to Wit, tho he have never so much Acumen and Facetiousness of Humour, yet his Impiety proclaims his Folly; he may have a lively Fancy, an Intriguing Cunning and Contrivance, and so may an Ape or a Fox, who probably if they had but Speech, tho destitute of Reason, wou’d outdo him in his own way; but he wants the Ingenuity of a Man, he’s a Fool to all Rational Intents and Purposes. She then who desires a clear Head must have a pure Heart; and she who has the first in any Measure will never allow her self to be deficient in the other. But you will say what degrees of Purity are requisite in order to Knowledge, and how much must we Know to the end we may heartily endeavour to Purify?