Sīmiyā’ is an Arabic word that uses to be translated as ‘white magic’ or ‘natural magic’. In fact, the so-called “science of al-Sīmiyā’” is a kind of magic well known in the Arab world since the Middle Ages. In this paper, after a short revision of the different etymologies suggested for this word, we discuss the definitions given to the this magical science by classic authors, namely Šhihāb al-Dīn al-Qarāfī (s. XIII), Ibn Jaldūn (s. XIV) and Hāyŷī Jalīfa (s. XVII), remarking the differences in their definitions.After that, we analyze the meaning, basic concepts and practice of the sīmiyā’ in al-Andalus, as exposed in the book entitled Kanz al-‘ulūm wa-l-durr al-manzūm, written by the sufi author Muhammad b. ‘Alī Ibn Tūmart al-Andalusī (s. XIII- XIV), what lead us to relatesufism with the practice of occult sciences in the Islamic world.