Doubt begins only at the last frontiers of what is possible.
Ambrose Bierce

Emigration, forced or chosen, across national frontiers or from village to metropolis, is the quintessential experience of our time.
John Berger

I am astonished each time I come to the U.S. by the ignorance of a high percentage of the population, which knows almost nothing about Latin America or about the world. It's quite blind and deaf to anything that may happen outside the frontiers of the U.S.
Eduardo Galeano

I belong to a nation which over the past centuries has experienced many hardships and reverses. The world reacted with silence or with mere sympathy when Polish frontiers were crossed by invading armies and the sovereign state had to succumb to brutal force.
Lech Walesa

I do not see how a man can work on the frontiers of physics and write poetry at the same time. They are in opposition.
Paul Dirac

If we want to talk about freedom, we must mean freedom for others as well as ourselves, and we must mean freedom for everyone inside our frontiers as well as outside.
Wendell Willkie

If you think there are no new frontiers, watch a boy ring the front doorbell on his first date.
Olin Miller

In particular, the efforts to reestablish peace after the World War have been directed toward the formation of states and the regulation of their frontiers according to a consciously national program.
Christian Lous Lange

In this world, shipmates, sin that pays its way can travel freely, and without passport; whereas Virtue, if a pauper, is stopped at all frontiers.
Herman Melville

Let us never forget this: since the day of the air, the old frontiers are gone. When you think of the defense of England you no longer think of the chalk cliffs of Dover; you think of the Rhine. That is where our frontier lies.
Stanley Baldwin

Liberty has restraints but no frontiers.
David Lloyd George

Modern science is fast-moving, and no laboratory can exist for long with a program based on old facilities. Innovation and renewal are required to keep a laboratory on the frontiers of science.
Burton Richter

Modern techniques have torn down state frontiers, both economical and intellectual. The growth of means of transport has created a world market and an opportunity for division of labor embracing all the developed and most of the undeveloped states.
Christian Lous Lange

New discoveries in science will continue to create a thousand new frontiers for those who still would adventure.
Herbert Hoover

Poetry is like a bird, it ignores all frontiers.
Yevgeny Yevtushenko

Right knows no boundaries, and justice no frontiers; the brotherhood of man is not a domestic institution.
Learned Hand

Russia knows of the vulnerability of her frontiers in this part of the world.
Aly Khan

Science is a field which grows continuously with ever expanding frontiers.
John Bardeen

Since the day of the air, the old frontiers are gone. When you think of the defense of England you no longer think of the chalk cliffs of Dover; you think of the Rhine.
Stanley Baldwin

Thank God we're going to try to continue and effectively defend our frontiers with the Border Patrol, with the Customs Department, with the Coast Guard, with the Armed Forces.
Barry McCaffrey