Reason & Fearless Speech

Dear colleagues,

I came across this quote in Fearless Speech and am particularly intrigued
with the last sentence.
 "It would be interesting to compare Greek Parrhesia with the modern
Cartesian concept of evidence. For since Descartes, the coincidence between
belief and truth is obtained in a certain (mental) evidential experience.
For the Greeks the coincidence between belief and truth does not take place
in a mental experience but in parrhesia.
It appears that parrhesia in the Greek sense can no longer occur in our
modern epistemological framework." ( p. 14).

I would appreciate suggestions on other sources of Foucault's work where he
explores this theme of fearless speech and the transformation of
subjectivity. 
many thanks
Ravinder