This is a great question.
When we read literature, we enter into a new world. This means that we begin to think the thought of others. In other words, we begin to see things from the perspective of others. This enables us to see gain new insights. Our eyes are opened.
This is important because we all have what sociologists call a commonsense view of the world. The problem with this is the people from other places in time and place have a different commonsense worldview. Therefore, our plausibility structures (another sociological term) differs from that of others. For example, we might think that the belief in the divine is absurd, but for other people the thought of the divine is the most natural thing.
In light of these points, the more we read literature, the more we will consider others. Keep in mind that literature (especially from another place) is a whole new worldview. The more our blind spots will be exposed, the more our eyes will be opened in new ways. To think outside our box, think in the box of another. Reading literature is a perfect way to start.