“Our particular causality scheme has brought us to a modest and rudimentary, although in many respects heroic, series of explorations. But it is far inferior to what might have been, and may one day be.”

“It goes with a courageous intent to greet the universe as it really is, not to foist our emotional predispositions on it but to courageously accept what our explorations tell us.”

“Planetary exploration satisfies our inclination for great enterprises and wanderings and quests that has been with us since our days as hunters and gatherers on the East African savannahs a million years ago. By chance—it is possible, I say, to imagine many skeins of historical causality in which this would not have transpired—in our age we are able to begin again.Exploring other worlds employs precisely the same qualities of daring, planning, cooperative enterprise, and valor that mark the finest in military tradition. Never mind the night launch of an Apollo spacecraft bound for another world. That makes the conclusion foregone. Witness mere F-14s taking off from adjacent flight decks, gracefully canting left and right, afterburners flaming, and there’s something that sweeps you away—or at least it does me. And no amount of knowledge of the potential abuses of carrier task forces can affect the depth of that feeling. It simply speaks to another part of me. It doesn’t want recriminations or politics. It just wants to fly.”

“We are made of stellar ash. Our origin and evolution have been tied to distant cosmic events. The exploration of the cosmos is a voyage of self-discovery.”

“In more than one respect, the exploring of the Solar System and homesteading other worlds constitutes the beginning, much more than the end, of history.”

“In the way that scepticism is sometimes applied to issues of public concern, there is a tendency to belittle, to condescend, to ignore the fact that, deluded or not, supporters of superstition and pseudoscience are human beings with real feelings, who, like the sceptics, are trying to figure out how the world works and what our role in it might be. Their motives are in many cases consonant with science. If their culture has not given them all the tools they need to pursue this great quest, let us temper our criticism with kindness. None of us comes fully equipped.”

“Science is far from a perfect instrument of knowledge. It's just the best we have. In this respect, as in many others, it's like democracy. Science by itself cannot advocate courses of human action, but it can certainly illuminate the possible consequences of alternative courses of action.”