Here's the meaning behind the secret message Andy sent to Red in Ellis "Red" Redding didn't have to trust Andy Dufresne blindly. Frank Darabont's 1994 adaptation of Stephen King's novella Rita Hayworth and Shawshank Redemption is one of the most highly-regarded movies in the history of cinema. Its airtight screenplay, first-rate performances, and heartfelt depiction of life in prison made audiences feel as though they were living side-by-side with the characters for decades inside Shawshank State Penitentiary, but that hasn't prevented some burning questions from persisting to this day.
The most popular of those questions is how Andy Dufresne (Tim Robbins) managed to escape through his makeshift tunnel and hide it with a Raquel Welch poster, but many cinephiles and Shawshank fans have already come up with plenty of answers for that (he taped it by three of its corners or only by the top). An almost equally persistent question is how Red (Morgan Freeman) found Andy after finally being released from Shawshank with such vague clues, given that Andy had previously showcased how deviously untrustworthy he could be under his innocent persona. As is the case with the rest of the movie, one little detail explains it all.
Andy didn't fully elaborate on his escape plan to Red because, albeit involuntarily, Red could have tipped off the authorities. Every single part of Andy's plan was vital for live the rest of their lives in freedom. And the specific choice of obsidian was made for the precise meaning of the stone itself.
Aside from ensuring their security, this extra step in Andy's plan also tested Red's willingness to keep living exactly at the moment he was questioning his new life outside of Shawshank. Red saw where Brooks ended his life firsthand and got a bitter taste of how overwhelming daily life was outside of prison, which made him struggle with the uncertainty of the future. Fortunately for him, Andy's quest forced him to maintain hope - the main theme of the movie - and take a risk. Andy specifically chose obsidian to signal Red's forthcoming treasure because the material is considered the "Stone of Truth" in spirituality and is often used to signify a promise of great wealth – as well as being a signal that Andy himself was being truthful. This, of course, is coupled with the redemption and rebirth that the oak tree represents, as it is the place where Andy had asked his wife to marry him.
Andy Dufresne is a brilliant man. His determination and genuine friendship with Red are part of what have made The Shawshank Redemption one of the highest-rated movies of all time, and these little details shouldn't go unnoticed. Although some parts of Andy's master plan relied heavily on faith and sheer luck (What if the warden had dared to open the Bible? What if Red had forgotten the name of Zihuatanejo?), his undying hope for a better tomorrow complemented them.
