“Great writing does not persuade; it takes the reader out of himself.” 

This quote reflects the treatise’s central theme: the sublime in literature. The sublime is a quality of a work of art that conveys great emotional power that makes the reader “lose himself” or become totally absorbed in the work. This quality is contrasted with writing that concentrates on rational persuasion and argument, and lacks that quality of strong emotion.

“The startling and amazing is more powerful than the charming and persuasive, if it is indeed true that to be convinced is usually within our control whereas amazement is the result of an irresistible force beyond the control of any audience.” 

This quote contrasts the sublime with the persuasive, preferring the former for its emotional power. This preference reflects Longinus’s priorities as a literary theorist. He values the sublime because it overwhelms the reader with a sense of irresistible power beyond human reason or control.

“Great qualities […] need the bridle as well as the spur.” 

In discussing the relative importance of natural genius (talent) and training, Longinus affirms the need for a balance between the two. Against those who claim that talent alone is necessary for writing well, he emphasizes the need for training, because it tames the sometimes unruly energy of genius.