What does Chillingworth say is the source of Dimmesdale's strange illness? In order to treat the illness what does he do?

believes that the
source of the Reverend 's illness is something spiritual rather than physical. For this reason,
he

strove to go deep into his patients bosom, delving
among his principles, prying into his recollections, and probing everything with a cautious
touch, like a treasure-seeker in a dark cavern.

In an
attempt to ascertain the cause and nature of whatever ails the minister, Chillingworth attempts
to get to know him as well as one can know another, to dive deeply into the minister's mind to
learn him inside and out. When we read this part of the text, the description of Chillingworth's
activity paints him as incredibly intrusive and ever-present. He is always there with
Dimmesdale, always watching and lurking and waiting. He comes to believe that something
significant is troubling the minister's conscience, and he finally confirms this belief when he
see something on Dimmesdale's chest (while the minister sleeps) that seems to indicate that he
is, in fact, 's co-sinner and 's father. He cannot treat this illness; in fact, he attempts to
make it worse because he wants Dimmesdale to pay and suffer for his
actions.