One of the main problems in modem philosophy, especially in the phenomenological movement, is the problem of intentionality. It was first proposed by Brentano as the characteristic feature of mental phenomena and later developed and completed by his student Edmund Husserl, who made it a fully-fledged philosophical theory. Even if the theory of intentionality is sometimes traced back to medieval authors such as Thomas Aquinas, Alexander Hales, Duns Scotus and others, the Islamic contribution to the problem is rarely acknowledged and, even when mentioned, it is cursorily dismissed as peripheral and insignificant.