 There are many possible interpretations as to why this discipline was originally called "kalam"; one is that the widest controversy in this discipline has been about whether the Word of God, as revealed in the Qur'an, can be considered part of God's essence and therefore not created, or whether it was made into words in the normal sense of speech, and is therefore created.The Mu'tazila were challenged by Abu al-Hasan Al-Ash'ari, who famously defected from the Mu'tazila and formed the rival Ash'ari school of theology.The Ash'ari school took the opposite position of the Mu'tazila and insisted that truth cannot be known through reason alone.