The Middle Ages are called the Dark Ages.

Due to social turmoil, the human nature and emotions of the body are weakened in art, and the beauty of all senses, body, and passions is doubtful, and the pursuit of spiritual justice is even more important. A symbol advocating abstinence and stillness. In literature, many theoretical books that are now considered very cult have also been produced.

Medieval artists valued the beauty of mathematics, so many symbols were born (also related to the rise of occultism), which I think is also very interesting.

12th century, Bavaria.