The divergent theories of inspiration that Swift satirized would continue, side by side, through the 18th and 19th centuries. Edward Young's "Conjectures on Original Composition" was pivotal in the formulation of Romantic notions of inspiration. He said that genius is "the god within" the poet who provides the inspiration. Thus, Young agreed with psychologists who were locating inspiration within the personal mind (and significantly away from the realm either of the divine or demonic) and yet still positing a supernatural quality. Genius was an inexplicable, possibly spiritual and possibly external, font of inspiration. In Young's scheme, the genius was still somewhat external in its origin, but Romantic poets would soon locate its origin wholly within the poet. Romantic writers such as Ralph Waldo Emerson ("The Poet"), and Percy Bysshe Shelley saw inspiration in terms similar to the Greeks: it was a matter of madness and irrationality.