Complex sentence: William Lilly (April 30,1602-1681), was a well-known English astrologer and occultist; he was particularly adept at interpreting the astrological charts drawn up and used in horary astrology, as this was his specialty.
Split into simpler sentences: William Lilly (April 30,1602-1681), was a very well-known English astrologer and occultist during his time. Lilly was particularly adept at interpreting the astrological charts drawn up and used in horary astrology, as this was his specialty.