“Poetry, if it is not to be a lifeless repetition of forms, must be constantly exploring "the frontiers of the spirit." But these frontiers are not like the surveys of geographical explorers, conquered once for all and settled. The frontiers of the spirit are more like the jungle which, unless continuously kept under control, is always ready to encroach and eventually obliterate the cultivated area.”

“There are frontiers to the mind which, once crossed, afford no return.”

“While the spirit of neighborliness was important on the frontier because neighbors were so few, it is even more important now because neighbors are so many”

“This is space. It's sometimes called the final frontier.(Except that of course you can't have a final frontier, because there'd be nothing for it to be a frontier to, but as frontiers go, it's pretty penultimate . . .)”

“We are shaped not only by our current geography but by our ancestral one as well. Americans, for instance, retain a frontier spirit even though the only frontier that remains is that vast open space between the SUV and strip mall. We are our past.”

“What we have been living for three decades is frontier capitalism, with the frontier constantly shifting location from crisis to crisis, moving on as soon as the law catches up. ”