The Greek term synaesthesia, which literally translates into 'perceiving together,' is known among most literary critics as the mixing of sensations. The term is applied in literature to the description of one kind of sensation in terms of another. For instance: 'hearing' a color or 'seeing' a 'smell.' That is, the description of sounds in terms of colors such as a "blue note;" of colors in terms of sound such as "loud shirt;" of sound in terms of taste such as "how sweet the sound;" and of colors in terms of temperature such as a "cool green." Although synaesthesia has been used by a variety of poets throughout the centuries, my focus will be on its use in the poetry of John Keats and Emily Dickinson. While critics and scholars have considered this subject before, normally it is approached in terms of its specific meaning within a particular poem. In contrast, I argue that Keats and Dickinson employ synaesthesia to crystallize a poetic perspective, a literary world view, and that this perspective significantly pertains to a variety of gender issues in the nineteenth century. Consequently, I contend that both poets were dealing with the large theme of an imaginative poetic world in which synaesthesia transmutes and synthesizes gender so that a "blue note," male and female, are radically the same and yet "other." After reviewing the scholarship of synaesthesia in Keats's and Dickinson's poetry, I will analyze a series of poems that illustrate my thesis, fleshing out the implications of a gender synthesis that makes us see both poets challenging and subverting the gendered commonplaces of the 19^th century.