Great discussion. It might be worth another article distinguishing between symbols of which the characters are aware, like the mocking jay in The Hunger Games, and symbols that the writer embeds for the readers without engaging the characters in the symbolism. Objective correlatives would belong the latter, I think.

(And Eliot's criticism of Hamlet seems far off the mark! The inability to articulate an external, "objective correlative" for Hamlet's inner self is acknowledged by Hamlet himself when he protests that his grief does not "seem" but "is." He claims that his mourning clothes, tears, sighs, etc. do

"not denote [him] truly, these indeed seem,

For they are actions that a man might play:

But I have that within which passeth show;

These but the trappings and the suits of woe."

(Act I, Scene II)

Hamlet cannot articulate whatever interiority he has "within," and "true" grief can indeed look like mourning clothes, tears, sighs, etc. The absence of any objective correlative is a brilliant choice, not a failure. Instead of using some external object, Shakespeare undermines externals as reliable realities and shows us the affect of that deep, inarticulate emotion, like Homer shows us the affect of Helen's beauty without describing her, and our imagination takes over.)