I love the word frontier which implies exploration and boundary which implies being boxed in. It’s the difference between open and close, curious and close-minded, building a wall and opening a gate.

Cicero is believed to be the greatest speaker that ever lived. So eloquent that Caesar–often the victim of the man’s words and redresses–considered Cicero‘s achievements to be more significant than his own; once remarking that it was nobler to “extend the frontiers of the mind” than it was to the “boundaries of the empire.”