Dualism is any doctrine holding that the universe originates from two independent and opposed principles. Islam recognised and fought against several forms of dualism, whose followers are called dualists, in Arabic thanawiyya . This word does not appear in the Qurʾān or in the ḥadīth , but it does occur in the title of two lost works, by, respectively, Abū l-Hudhayl (d. 227/841?) and al-Kindī (d. c. 256/870). This abstract technical term became current in the fourth/tenth century, but it seems to have been preceded by another