multiplicity of sensations
Mary Shelley posits the Lockean notion that at first one's natural condition is that of synaesthesia, an indiscriminate intermingling of sense experience: only when the intellect begins consciously to analyze sensory data are they broken down according to the five diverse senses. The physiological basis for this development had been posited in the mid-eighteenth century by the French materialist philosopher Condillac, in his Traité des sensations.
Deliberate synaesthesia is an artistic ploy often to be found among the English Romantic poets, in none more than Percy Bysshe Shelley: see, for instance, his poem of 1818, "Lines Written among the Euganean Hills," esp. line 285 ff.