When one goes over one's book ratings, one is often tempted to change a rating. Such situations reflect two facts:
1. Our tastes change as time goes by, and
2. Someone else's rating and profile photo make us change our mind.
As such, I propose that we take the time factor into consideration in book ratings. Rather than give a book a certain rigidly fixed amount of stars, we could have a timeline that goes, on the x-axis, from birth to death, with a singularity that represents the point at which we started reading the book. On the y-axis, why not, a value from 0 to 10.
Along the timeline, we could annotate the major changes in the rating we attribute to the book. For instance, if at a time T our rating skips from a 4 to a 7, one can attach a little explanatory note to just that point in the timeline that states "I realized the story is symbolic and that it doesn't imply that real people can have superpowers" or "More of a 7 than a 4, really, when you take into account it was written before computers were invented and nevertheless managed to fit in a LOT of words!".
Then, then, get this: you could have an ANIMATION that shows your favorite books and as time is cycled from 0 to death you watch as the top 10 reorders itself, children's books fall off the list and books with cynical anti-heroes creep up to the top. And then, at the moment of the reader's death, the list emits a (relatively) blinding flash of light and the list fades into darkness. And then all the books the reader has ever read form the closing credits. A reader's life.
This is so beautiful I am literally crying as I write this, and yes I know the meaning of "literally"...wait, no I didn't...ok figuratively crying as I write this.