The first quote is a mistranslation, propagated by Robert Kennedy in his famous speech following the assassination of Martin Luther King, Jr. It is based on the Edith Hamilton translation, which may not be the most accurate to begin with. Further discussion on this quote. The Grene / Lattimore translation reads:
"Still there drips in sleep against the heart / grief of memory; against / our pleasure we are temperate / From the gods who sit in grandeur / grace comes somehow violent."
- Aeschylus (Agamemnon, lines 178-183)
Still, this is a very famous version of the quote, and has reached a level of cultural currency on its own. It is probably worth preserving in some form, though with a note as to the origins.