Thanks to Dan Brown, everyone has one of two responses to the idea that there are hidden codes in ancient works: Either you immediately believe them, because of that mind-blowing Da Vinci Code book, or you immediately mock them, because of that bullshit Da Vinci Code book.
The truth is somewhere in the middle. There are, after all, some fairly weird encoded messages that actual academic types have identified. And some of them are even about Freemasons.
Encoded Messages About: Jewish mysticism.
Cracked has mentioned before that Michelangelo appears to have cleverly painted God to look like a giant brain in his Sistine Chapel fresco...
... but according to a prominent professor at Yeshiva University, the rabbit hole goes much, much deeper than that: Michelangelo's work is packed full of symbols of Jewish mysticism. You may also know this as kabbalah, aka the religion Madonna made popular in Hollywood a few years ago.
T-shirt evangelism is famously effective.
What we know is that for a while Michelangelo was living with a politician in Florence named Lorenzo de' Medici, who was apparently part of the whole kabbalah scene at the time. Also, we know Michelangelo never tired of painting subtle screw-yous to the Catholic church into his work.
So, in kabbalah, the Hebrew letter gimel symbolizes g'vurah, or justice and punishment. Here it is next to the Sistine Chapel's depiction of David, laying the holy smack down on Goliath: