William Lilly (May 11, 1602 - June 9, 1681), was an English astrologer. His most comprehensive book was published in 1647 and was entitled Christian Astrology. It remains popular even today and has never gone totally out-of-print. It is considered one of the classic texts for the study of traditional astrology from the Middle Ages, in particular horary astrology, which is mainly concerned with predicting future events or investigating unknown elements of current affairs, based on an astrological chart cast for the time a particular question is asked of the astrologer. He caused much controversy in 1652 for allegedly predicting the Great Fire of London some 14 years before it happened. For this reason many believed that he might have started the fire, but there is no evidence to support these claims. He was tried for the offense in Parliament but was found to be innocent. After the Restoration he very quickly fell into disrepute. He retired to a small estate in Surrey where he briefly practiced medicine. He died in 1681 at the age of 79.