Scholars of this period include Varahamihira and Aryabhata, who is believed to be the first to consider zero as a separate number, postulated the theory that the Earth rotates about its own axis, and studied solar and lunar eclipses. Kalidasa, who was a great playwright, who wrote plays such as Shakuntala, and marked the highest point of Sanskrit literature is also said to have belonged to this period. The Sushruta Samhita, which is a Sanskrit redaction text on all of the major concepts of ayurvedic medicine with innovative chapters on surgery, dates to the Gupta period.