Prince Kālaka was the son of King Vajrasiṃha and of Queen Surasundarī in the town of Dharāvāsa and an accomplished young man. Once he went for a horse ride in a park. He heard a deep voice and went towards it. He discovered that the voice was that of the Jain monk Guṇasundara, who was teaching. He sat down to listen to him respectfully. Convinced by the teaching, Kālaka asked his parents' permission to enter monastic life. The Kālakācārya-kathā – Story of the Religious Teacher Kālaka – emphasises the connection between religious practice and magical abilities. As an accomplished Jain teacher, Kālaka can master various magical sciences and transmute brick into gold. He uses his powers to help the Śakas, a foreign population. In exchange, the Śakas help him destroy the wicked king, Gardabhilla. This eventful tale belongs to the Śvetāmbara Jain tradition. It is known in several versions in various languages and is often illustrated. The story is frequently found as an appendix to the Kalpa-sūtra because the last part of the story explains how Kālaka changed the date of Paryuṣaṇ. This annual festival was moved from the fifth day of the bright half of the month Bhādrapada – roughly equivalent to August to September – to the fourth. The Kalpa-sūtra has a central role in Paryuṣaṇ. The version of the story here is one known as Śrīvīravākyānumatam. These are the words that start the text. It is written in Sanskrit and represents a short recension, where the story is told in simple language without poetical embellishments. By an unknown author, it is one of the most popular versions.