6. The second way is, by purity of heart and life: for as vice not only proceeds from ignorance, but also causes it, by besotting and clouding the understanding, so purity not only proceeds from knowledge, but also produces it, making the soul see more clearly and distinctly. And the same method is recommended in scripture, _Wisdom_, says the wise man, _will not enter into a polluted spirit_. So the angel to _Daniel_, _Many shall be purified and made white, and none of the wicked shall understand, but the wise shall understand_. To this purpose too, is that of our Lord, above repeated; _He that followeth me, walketh not in darkness_; the purity of his heart is a light to his understanding. 7. But to represent this more clearly; there are two ways whereby purity of heart serves to the acquirement of knowledge; by natural efficacy, and by the divine blessing. And first, by natural efficacy, either by clearing the medium, or by assisting the faculty. As to the former, we are assured, not only that the soul now sees through a medium, and that this medium is the body, but likewise that the grossness of this medium hinders the sight of the soul. Whence it follows, that whatever helps this medium, helps the sight of the soul. And this purity does; especially that eminent part of it which consists in chastity and temperance. For first, it composes the passions, especially that of lust, by that the animal spirits, and by that the blood. For the motion of the passions ferments the spirits, and the fermentation of the spirits agitates the blood, and by that agitation raises all the feculent and drossy parts of it, and makes it like a troubled fountain, thick and muddy. And therefore it is, that men in any passion can’t reason so clearly, as when they are in more quiet and silence of spirit. But by purity all this disturbance is allayed, the passions are becalmed, the spirits fixed, the fountain of the blood cleared up, and so all the inner part of the glass, through which we see, becomes more bright and transparent, more apt to transmit the rays of light to the soul, which consequently sees more clearly through it. 8. But this is not all: for purity clears the outward part of the glass too. First by consequence, because the finer the spirits and blood are, the finer will be the threads of the outward veil also. Then more directly; because temperance refines and subtilizes the texture of the body, and diminishes its bulk and grossness, and unloads the soul of a good part of that burthen, which not only presses down her aspirations, but also hinders her sight.