Thank you very much. I still need your help to revise a few more lines.
1) A quietus was a statement which released an accountant from his responsibility for the accounts he was working on; the full Latin phrase was quietus est, “it is at peace”, i.e. there is no further dispute over the exact amount in the account.
2) It would only take a small knife to bring relief but the fear of something after death, expressed in the image of the unknown country from which no traveller comes back paralyses the will and prevents self-destruction.
3) There is a clear relationship between “conscience” and “consciousness” or the power of thought. The pale cast of thought turns the native hue of resolution pale and sick. The natural colour of resolution is made look sick by the paleness (pale cast) of reflection.
1. Be sure to put the phrase quietus est in italics, since it's not an English phrase.
http://www.dailywritingtips.com/italicizing-foreign-words/
Italicize and put a comma after i.e.
2. commas needed - do you see where?
3. Text seems a bit obscure. Can you clarify?