This chapter offers readings of poems by William Cowper and Samuel Taylor Coleridge which help trace the impact of the ancient Hippocratic medical heritage of recovery from forms of mental illness on each poet’s envisioning of the sublime in nature. The experience of fear and awe before the world is, I argue, reflective of a turn in the weight of credence given to positive perceptions of the natural world which its sanative use in treating forms of mental ill-health made possible. This influence is seen reflected in poems by both authors that utilize an oceanic setting and fluid metaphors to chart this change in sensibility.