This thesis adopts the medieval medical discourse on love melancholy to analyze the representation of erotic love in Keats¡¦s poetry and to the changes in his ideas concerning love. In medieval discourse on love melancholy, women are seen as demonic agents to seduce men. In the process of their seductions, these temptresses also use amatory magic and love philters to bewilder and to enthrall their ¡§games.¡¨ People who fall in love usually lose their minds, their senses, and their judgments. They appear obsessed and insane, which leads to weakness, absurdity, and mental obscurity. Many of Keats¡¦s poems depict lovesickness, such as ¡§Lamia¡¨ and ¡§La Belle Dame sans Merci.¡¨ There are evidences showing that when he was composing these poems, he was also reading medieval treaties on love melancholy, which suggests that he might to a great extent be influenced by medieval concepts on lovesickness and sexuality. The characters in these poems, furthermore, can be seen as representations of the medieval images of the ¡§agents of love,¡¦ who, usually female, seduce men and cause all kinds of symptoms of ¡§love.¡¨ Keats was influenced by medieval discourse on lovesickness not only in his poetry but also in his personal life. When he first fell in love with Fanny Brawne, seemed to act under the influence of the so-called ¡§love-sickness,¡¨ and he strived to escape from love. Nevertheless, his failure to cure himself of this ¡§disease¡¨ enabled him to perceive the restraining viewpoint of this medieval discourse in regard to being love sick. Realizing this restrictive rational ideology lurking behind the medieval ideas of love melancholy and sexuality, Keats changed his belief in lovesickness. With Lycius¡¦s accusation of Apollonius and the knight¡¦s aimless loitering, he satirizes in ¡§Lamia¡¨ and ¡§La Belle Dame sans Merci¡¨ the derogation of reason on lovesickness, while in ¡§the Ode on Melancholy¡¨ and ¡§To Autumn,¡¨ Keats represents melancholy in a way that differs from the discourse he has inherited. Instead of showing feminine beauty as threatening and haunting, he delineates it as giving a perplexing delight. Rather than sober male characters, he prefers and describes indecisive male characters in love who demonstrates qualities such as softness, capriciousness and uncertainty¡Xqualities usually associated with females. Keats came to realize that the female perplexing beauty is suppressed and disliked in a society dominated by men, and males were not allowed to express feminine traits and emotions. The emphasis on rationality in late-eighteenth century somewhat resembled the medieval times in that both emphasize male calmness and intelligence. However, experience enabled Keats to realize that, rather than singularly repel the feminizing symptoms aroused by love melancholy, it is healthier to accept both the female and male features demonstrated within a man. Emotional perturbation and temporary irrational passions are human emotions that should be permitted. Instead of running away from love, Keats with his insight into lovesickness cured his fear for lovesickness. The idea of medieval sexuality no longer haunted on Keats on his journey to love, but is criticized for its excessive rationality.