The Epistle concerning Dreams is a little known work where Avicenna deals with some relevant considerations regarding the way in which prophecy and veridical dreams take place. The theory contained in this- treatise accurately illustrates how intricate Avicenna’s theory of prophecy is and, at the same time, provides several clues in order to recognize the origin of this theory as it appears in major treatises such as fī al-Nafs and Ilahiyat of the Šifa’. The Risala al-Manamiyya also enables us to (...) recognize the impact of several influences coming from the Ancient Greek tradition—mainly from Aristotle, Galen, Plotinus, and other Neoplatonics. This article explains the theories of divination by means of dreams and the conception of prophecy, as they appear in the Arabic version of the De divinatione per somnum, a treatise where the origins of Avicenna’s theory of prophecy can be found. Furthermore it shows the impact that the theory contained in this treatise had in the Risala al-Manamiyya. Finally, it expounds some remarks regarding the transmission and adaptation of the metaphysical and psychological points of view posed both in the Arabic version of the De divinatione and the Risāla al-Manāmiyya, alluding to the impact they had in the theories of prophecy found both in Avicenna’s major treatises in the Šifā’. (shrink)