Gary Goldschneider (22 May 1939 – 5 October 2019) was a writer, pianist, composer, and personologist. He is known for writing the Secret Language personological book series, based on astrology, numerology, and tarot, in which he studied and assessed character traits of over 14,000 people to generalize birth characteristics for each day of the year. In addition, Goldschneider has performed several "marathon" piano pieces, such as playing all 32 of Beethoven's sonatas in one sitting. On another occasion in Nevada City, California, in 1984, he performed all of Mozart's sonatas in one sitting, only taking three breaks to consume water. This took approximately six hours.