A mirror reflects light. It reflects an image. A mirror produces an accurate representation of something else. A replica. Rey’s Reflections, in other words, Rey is a reminder of those that have come before: Han, Luke, Leia, and possibly, deeper down the line. She's a Reality Check for the Big 3, without her none of them would be able to connect again (not literally, but figuratively speaking) and come full-circle in their story.
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A Picture is Worth a Thousand Words:
Redemption is a continuous theme in Star Wars. But, is that trope getting old? Is it time for something new? After all, the Star Wars stories have evolved with the sequel trilogy, so maybe Kylo Ren is right? It's time to let old things die. Kill the past. To redeem or not to redeem, that is the question.
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A Picture is Worth a Thousand Words: