Sciences usually advances by a succession of small steps, through a fog in which even the most keen-sighted explorer can seldom see more than a few paces ahead. Occasionally the fog lifts, an eminence is gained, and a wider stretch of territory can be surveyed-sometimes with startling results. A whole science may then seem to undergo a kaleidoscopic rearrangement, fragments of knowledge sometimes being found to fit together in a hitherto unsuspected manner. Sometimes the shock of readjustment may spread to other sciences; sometimes it may divert the whole current of human thought.

To travel hopefully is better than to arrive.

The plain fact is that there are no conclusions. If we must state a conclusion, it would be that many of the former conclusions of the nineteenth-century science on philosophical questions are once again in the melting-pot.

Put three grains of sand inside a vast cathedral, and the cathedral will be more closely packed with sand than space is with stars.

Science should leave off making pronouncements: the river of knowledge has too often turned back on itself.

The motion of the stars over our heads is as much an illusion as that of the cows, trees and churches that flash past the windows of our train.

Life exists in the universe only because the carbon atom possesses certain exceptional properties.