The goddess Isis and her search for Osiris (her brother and consort) is commemorated on this day by the Lychnapsia (Festival of the Lights of Isis). Dried rose petals and vervain are burned in small cauldron pots or incense burners as offerings to Isis, and green candles are lit in her honour.
Shared from http://www.wiccazone.net/wiccan_august.htm
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