As it is with spiritual discoveries and affections given at first conversion, so it is in all subsequent illuminations and affections of that kind; t… - Jonathan Edwards

So that it must be only by the imagination that Satan has access to the soul, to tempt and delude it, or suggest anything to it. And this seems to be the reason why persons that are under the disease of melancholy are commonly so visibly and remarkably subject to the suggestions and temptations of Satan... Innumerable are the ways by which the mind may be led on to all kind of evil thoughts, by the exciting of external ideas in the imagination.

Religion consists much in holy affection; but those exercises of affection which are most distinguishing of true religion are these practical exercises. Friendship between earthly friends consists much in affection; but those strong exercises of affection that actually carry them through fire and water for each other are the highest evidences of true friendship.

From the blinding deceitful nature of sin. The heart of man is full of sin and corruption, and that corruption is of an exceedingly darkening, blinding nature. Sin always carries a degree of darkness with it; and the more it prevails, the more it darkens and deludes the mind. — It is from hence that the knowing whether there be any wicked way in us is a difficult thing. The difficulty is not at all for want of light without us, not at all because the word of God is not plain, or the rules not clear; but it is because of the darkness within us.