Fred Sanders, at The Scriptorium, lists and discusses eight characteristics or criteria of a great book. I've listed the eight, but to read his discussion of them you'll have to visit his article: He writes that a great book...
- speaks from an important original setting.
- is written in a way that is relevant for readers today.
- is well-crafted.
- is one that provokes excellent discussion.
- is inexhaustible, so no reading of it is the final reading, and no discussion ever runs it dry.
- is time-tested. People from multiple generations have had their hands on it, and have judged it to be worth passing along.
- is weird. It’s got angles, edges, textures, and stuff sticking out that you wouldn’t have predicted.
- is smarter than the best teacher, but within reach of the average student.