Longinus argues that the test of excellence in literature is whether it achieves the status of being sublime. He further goes on to describe what he means by this word by saying that sublime literature has an unmistakable impact on the reader that results in their soul becoming elevated. Note how Longinus describes this impact:
For, as if instinctively, our soul is uplifted by the true sublime; it takes a proud flight, and is filled with joy and vaunting, as though it had itself produced what it has heard.
The metaphor of flight is therefore used to describe the impact of excellent literature in depicting the effect it has on the reader. The second definition that Longinus gives the reader of sublime literature is that it can be re-read any number of times without losing its original impact. Longinus argues that sublime literature has to "please all and always," because such literature captures something about the essence of humanity that is unchanging and will never diminish in value.