I've always loved symbolism in literature. Foreshadowing is great but what makes reading great authors transcendent (above let's say, internet click bait content generators) is symbolism. The Art of Analogy can demonstrate how effective your own imagination really is. Metaphor, simile, all that stuff we learned in high school. For me it was the only thing that made school tolerable. It sure wasn't gym class. It was lunch hour comedy hour with the Jewish boys and finding hidden meaning in Shakespeare. The subtext IS the message. Ohhhh, I get it. One of the few things I discovered as a teen that had nothing to do with the terrifying plunge into nudity and birth control that was hormonal development. Which, looking back, I acknowledge was a tragic pre-occupation and an overrated pursuit.
