A young drowned was not a very common subject in mid-nineteenth century paintings. This allowed the artist to experience the endless possibilities related to the absence of grace and poise.
When Ophelia dies, passing "from her melodious lay to Muddy death", she becomes an impossible object of desire. That's Ophelia for Hamlet: the ideal of feelings.
In her delirium, Ofelia wanders by a lake, picking flowers, and dies by drowning in the muddy waters. This image symbolizes the ultimate madness, disease of the cerebellum, which is the nucleus of the neurospinal system, the sensations produced by dementia in those organs are transmitted to more sympathetic with it. Such transmission and sympathy purely organic cannot be hidden nor mastered when the dominator of sensations has died : reason. If it coincide in dementia sensation with memory, it's not memory that determines sensation, this is not a reminder of reality.