Molly Hall at About Astrology posted a link to Linda Moulton Howe’s excellent crop circle site where she compares the latest crop circle to a sigil used by the ancient alchemists. Linda writes:
Sigils are codes created for a specific magical purpose. The pattern is the code derived from a number and/or letter grid known only to those who produce sigils from the known grid. A sigil is usually made up of a complex combination of several specific symbols or geometric figures each with a specific meaning or intent. The term sigil derives from the Latin sigillum meaning “seal,” though it may also be related to the Hebrew segulah meaning “word, action or item of spiritual effect.”
There is sigil magic in which symbols and signs are used as tools of magicians and alchemists. In medieval ceremonial magic, sigils represented various angels and demons that the magician can summon. The magical training books called the Grimoires often listed pages of angel and demon sigils. A particularly well-known list is in the Lesser Key of Solomon, in which the sigils of the 72 princes of the hierarchy of hell are given for the magician’s use, including the demon Aim. Such sigils were
considered to be the equivalent of the true name of the spirit, and thus granted the magician a measure of control over the entities being called.
For example: