Panthan or Panth (meaning "way" in Sanskrit) refers to a number of religious systems in India. A panth is frequently headed by scholars or senior practitioners of the tradition and is formed by a guru or an acharya. The term also refers to one of the main schools of Hinduism, founded in the 15th century by Guru Nanak. It spread across northern India and Nepal and remains popular among many Sikhs. Pantheons are lists of saints or heroes that serve as models for Christians to follow. They are usually composed of members of a single church or group who have been acknowledged for their contribution to the cause of Christ. According to John Calvin: "We must remember that our Savior has purchased us with His own blood; therefore, let us show our gratitude by loving and serving others with like sacrifice." The word "pantheon" comes from two Greek words meaning "all gods" or "every god". It was first used by Clement of Alexandria (c. 150-215) to describe the collection of ancient Greek gods worshiped by the Roman people. The pantheon was made up of all the major gods as well as a number of minor ones. In Judaism, a pantheon is a list of idols or images of God's names.