Emily Dickinson and Gerard Manley Hopkins have often been described as “protomodernist” poets. However, the term protomodernist has been employed in imprecise ways, encompassing both intellectual and aesthetic aspects of their work. In response, this essay argues for an aesthetic definition of modernism that focuses on the poets' experimentation with the medium. By way of illustration, it examines Dickinson's and Hopkins's experimental use of rhyme, arguing that their stylistic innovations, rather than their worldviews, mark them as protomodernist. With reference to concepts in aesthetics drawn from figures such as Kant, Hegel, and Rancière, as well as critical perspectives on, and quantitative analysis of, the poets' rhyming experiments, this essay further contends that Dickinson's and Hopkins's use of rhyme constitutes not a superficial embellishment but rather a central component of their poetic thinking.