Delusion

Can delusion be conceptualized as an embedded mind state in the individual before the grammatical form of the word, "delusional" existed?

Or when the mid-night Hour is told,
And drooping Lids thou still do'st waking hold,
Thy fond Delusions cheat the Eyes;
Before 'em antic Spectres dance,
 -Pg 23 Anne Finch

We have here a different kind of misinterpretation of the insane, something equally madness as defined by a multitude, but a multitude in ones, ending though, with the same old confirmation of a half-truth. Maria and Yorick walk in together, each supporting the other's delusion.
-Pg. 104 Madness of the Multitude

    A common theme with delusion in the 18th century is it's association with the sensory. It is often conceptualized as being separate from the sensory, however having a downstream effect on it. We also notice when delusion exists separate from the individual. The poem by Finch supports this commonality. "Thy fond Delusions" implies that the individual is in possession of them, rather them being a mind state embedded in the person. Possession of a mind state denotes separation because to possess something, there must be a boundary between the individual and the mind state. I am running into a difficulty with this concept in my paper, while curiosity is described as if embedded in the individual (ie. she is curious); the word that would describe an embedded delusion is "delusional" (as in she is delusional) however the OED doesn't site this word as being used until 1871. The thesis of my final paper rests on the crux that mind states can be framed as embedded and separate from the individual. In curiosity, the grammatical form of the word suggested it's embedded or separateness. I wonder, if I could use the grammatical style used when it is addressed to indicate a state of embedded or separateness.
     The description of delusion follows a description of dreams. Dreams we know, occur in the mind, separate from the senses. There is a contrast between the delusion and dream in the poem because of the word "Or"; however it is not the realm of functioning that seems to be contrasted, but rather the state of consciousness. In dreams, the individual is intruded by shadows during sleep, however during delusion this occurs when "thou still do'st waking hold". "Thy fond Delusions cheat the Eyes" implies that delusions are separate from the eyes, the sensory component, because they are able to perform an action on them, cheat them. Delusion is being framed as separate from the individual and from the sensory.