What are the transmutation circles in Fullmetal Alchemist based on, if anything? The transmutation circles in Fullmetal Alchemist always looked familiar to me, but I could never place my finger on why. What, if anything, are they based on?
This site has a note about "Squaring the circle", describing a utilization of circles:



Attributed to Michael Maier, a German alchemist from the 17th century. That gives you the generalized "simple" transmutation circle:



The symbols used in some of the more complex circles are old alchemic symbols or variations of them. I don't know of a complete list of them but some of them can be seen in Annibal Barlet's works or other symbols from the 17th century. The inscriptions themselves seem to mostly come from George Ripley's 12 Gates.