Chaucer and Ibn al-Haytham (Alhacen): Perspectiva, Arabic Mathematics, and Acts of Looking

The question of "how one sees" gives rise to a brief, learned interjection on optics and perspectiva in the Squire's unfinished, interlaced romance-an intervention that draws "Alocen," the Arabic mathematician Ibn al Haytham (Latin: Alhacen or Alhazen) into discussion. Alhacen's De aspectibus, the Latin translation of his extraordinary treatise Kita b al-Mana zir (Book of Optics) has long been acknowl edged and utilized in Chaucer scholarship. However, little focused attention has been paid to tracing the intertextual routes that lead to Chaucer's "Alocen" from Jean de Meun's reference to "Alhacem" in the Roman de la Rose, through to entries on "Ibn al Haytham" in Arabic bio bibliographic dictionaries. In tracing the ways that European vernacular literature can be connected with Arabic textual tradi tions, this article also challenges the under examined Eurocentric approaches to Chaucer and late medieval vernacular literature where Arabic figures such as "Alocen" have been collapsed into generic molds of medieval philosophers. It argues that repositioning Chaucer's "Alocen" as an Arabic mathematician and optical authority allows us to understand better not only his presence in The Squire's Tale, but the depiction of the physical act of looking and the cognitive and psychological consequences of key moments of sight beyond this romance. In order to demonstrate this, the exact question of "how one sees" as presented in the K i t a b a l -M a n a z i r is explored with particular attention paid to the psychol ogy of sight in examining the relationship between perception and judgment in three pivotal acts of looking in The Knight's Tale, The Physician's Tale, and Troilus and Criseyde.