Knowledge is indivisible. When people grow wise in one direction, they are sure to make it easier for themselves to grow wise in other directions as well. On the other hand, when they split up knowledge, concentrate on their own field, and scorn and ignore other fields, they grow less wise - even in their own field.

Life is a journey, but don't worry, you'll find a parking spot at the end.

Science is dangerous. There is no question but that poison gas, genetic engineering, and nuclear weapons and power stations are terrifying. It may be that civilization is falling apart and the world we know is coming to an end. In that case, why no turn to religion and look forward to the Day of Judgment, ... [being] lifted into eternal bliss ... [and] watching the scoffers and disbelievers writhe forever in torment.

Old men tend to forget what thought was like in their youth; they forget the quickness of the mental jump, the daring of the youthful intuition, the agility of the fresh insight. They become accustomed to the more plodding varieties of reason, and because this is more than made up by the accumulation of experience, old men think themselves wiser than the young.

There is no Master but the Master,” he said, “and QT-1 is his prophet.

A scientist is as weak and human as any man, but the pursuit of science may ennoble him even against his will.

At two-tenths the speed of light, dust and atoms might not do significant damage even in a voyage of 40 years, but the faster you go, the worse it is--space begins to become abrasive. When you begin to approach the speed of light, hydrogen atoms become cosmic-ray particles, and they will fry the crew. ...So 60,000 kilometers per second may be the practical speed limit for space travel.