"William Lilly (May 11, 1602 - June 9, 1681), was a famed English astrologer and occultist during his time. Lilly was particularly adept at interpreting the astrological charts drawn up for horary questions, as this was his speciality. He caused much controversy in 1666 for allegedly predicting the Great Fire of London some 14 years before it happened. For this reason many people believed that he may have had started the fire, but there is no evidence to support these claims.

William Lilly began to dabble in astrology, reading all the books on the subject he could fall in with, and occasionally trying his hand at unravelling mysteries by means of his art. The years 1642 and 1643 were devoted to a careful revision of all his previous reading, and in particular, having lighted on Valentine Naibod's Commentary on Alcabitius, he "seriously studied him and found him to be the profoundest author he ever met with." About the same time he tells us that he "did carefully take notice of every grandaction betwixt king and parliament, and did first then incline to believe that as all sublunary affairs depend on superior causes, so there, was: a possibility of discovering them by the configurations of the superior bodies." And, having thereupon "made some essays," he "found encouragement to proceed further, and ultimately framed to himself that method which he ever afterwards followed."

He then began to issue his prophetical almanacs and other works, which met with serious attention from some of the most prominent members of the Long Parliament. Lilly was on intimate terms with Bulstrode Whitelocke, William Lenthall the speaker, Sir Philip Stapleton, Elias Ashmole and others. Even John Selden seems to have acknowledged him, and probably the chief difference between him and the mass of the community at the time was that, while others believed in the general truth of astrology, he ventured to specify the future events to which he referred.