The state of interior nothingness is characterized, further, by the extinction of the power of antecedent evil habits. A person may be sanctified to God, his heart may be pure in the divine sight, and still there may be a constant struggle on the part of the "old man" or the "old nature," to regain possession. It is difficult to explain this, viz. that a truly holy heart may still have a struggle antagonistical to sin, and oftentimes a fearful struggle; but it is probably owing, in addition to the direct temptations of Satan, to the tremendous power of antecedent evil habits. The principle of self-love for instance, may by divine grace be redeemed from its selfish attitude, and may be brought to its true subjective position and become a holy principle; and yet in consequence of its previous habits of inordinate exercise, there may be a strong tendency, which requires constant resistance, to resume its former position of irregularity and sin. This tendency is not, properly speaking, in the principle itself; but is forced upon it exteriorly, if we may so express it, by the law of habit; and therefore although it is extremely dangerous, it does not appear to be necessarily sinful. The idea may here perhaps be illustrated in the case of the reformed inebriate. He has refrained from drinking; but the influence of the antecedent law of habit is still felt in his system. He is no longer guilty of the sin of drinking; but his liability to fall into this sin is greatly increased by his antecedent evil habit. There is, undoubtedly, something mysterious in this: but it seems, nevertheless, to be true. He feels that, in consequence of his former evil habits, the enemy is near at hand and in great power; that his danger is thereby increased, and that he must always be in the attitude of watchfulness and of resistance. Something like this is the case with those, who have just entered into that state where they can say, they "love the Lord with all their heart." The enemy is cast out; but he avails himself of the influence of the law of habit, to take a hostile attitude and to seek a re-entrance.
Now when a person has experienced the state of interior nothingness, as it is conveniently, perhaps, and yet not accurately termed, he has by divine grace, not only succeeded in conquering sin in the gigantic forms of creature-love and of self-will, but in breaking down the perplexing influence and the unfavorable tendency of former habits. And hence there is a vast accession to his power, and to his tendency to union with God, Satan himself, in the presentation of his temptations, has comparatively but little influence over such a soul. He has, comparatively speaking, no basis to operate upon, no way of secret, circuitous, and indirect attack; but must come boldly up and make his attack, face to face, as he did in his temptation of the blessed Savior. And this he would rather not do, if he can approach the object of his attack in some other way.
— edited from The Interior or Hidden Life (2nd edition, 1844) Part 3, Chapter 12 by Thomas Cogswell Upham. His blog is managed by Craig L Adams and can be found here: http://thomascupham.blogspot.com