Medieval natural philosophy illuminates Chaucer's use of the motif of sight and the relationship between love and knowledge. In this study, Norman Klassen shows how Chaucer explores the complexity of the relationship between love and knowledge through recourse to the motif of sight. The convention of love at first sight involves love, knowledge, and sight, but insists that the claims of love and the realm of the rational are in strict opposition. In the metaphysical tradition, however, the relationship between love, knowledge and sight is more complex, manifesting both qualitiesof opposition and of symbiosis, similar to that found in late medieval natural philosophy. The author argues that Chaucer is unorthodox in exploiting the possibilities for using sight both to express emotional experience and to accentuate rationality at the same time. The conventional opposition of love and knowledge in the phenomenon of love at first sight gives way in Chaucer's development of love, knowledge, and sight to a symbiosis in his lovepoetry. The complexity of this relationship draws attention to his own role as artificer, as one who in the process of articulating the effects of love at first sight cannot help but bring together love and knowledge in ways not anticipated by the conventions of love poetry.NORMAN KLASSENis a Social Sciences and Humanities Research Council of Canada postdoctorial fellow at the Centre for Medieval Studies and the Department of English Language and Literature at the University of Minnesota.