We can now see that it is not so hard to lead the life of heaven as people think, because it is simply a matter of recognizing, when something attractive comes up that we know is dishonest or unfair, that this is not to be done because it is against the divine commandments. If we get used to thinking like this, and from this familiarity form a habit, then we are gradually united to heaven. To the extent that we are united to heaven, the higher levels of our minds are opened, and to the extent that they are opened, we see what is dishonest and unfair; and to the extent that we see this, these qualities can be dispelled. For no evil can be banished until it has been seen. This is a state we can enter because of our freedom, since everyone is free to think in this way. However, once the process has started, the Lord works his wonders within us, and causes us not only to see evils but to refuse them and eventually to turn away from them. This is the meaning of the Lord’s words, “My yoke is easy and my burden light” (Matthew 11:30).
It is important to realize, though, that the difficulty of thinking like this and also of resisting evils increases to the extent that we deliberately do evil things—in fact, to that extent we become used to doing them until ultimately we no longer see them. Then we come to love them and to excuse them to gratify our love and to rationalize them with all kinds of self-deceptions and call them permissible and good. This happens, though, to people who in early adulthood plunge into all kinds of evil without restraint and at the same time at heart reject everything divine.
from Heaven and Hell, Section 533