Inspect every piece of pseudoscience and you will find a security blanket.

To test a perfect theory with imperfect instruments did not impress the Greek philosophers as a valid way to gain knowledge.

The Three Theorems of Psychohistorical Quantitivity: The population under scrutiny is oblivious to the existence of the science of Psychohistory. The time periods dealt with are in the region of 3 generations. The population must be in the billions (±75 billions) for a statistical probability to have a psychohistorical validity.

My feeling is that as far as creativity is concerned, isolation is required. Creation is embarrassing. For every new good idea you have, there are a hundred, ten thousand foolish ones.

It is the writer who might catch the imagination of young people, and plant a seed that will flower and come to fruition.

As artists and traders in medieval cities began to form organizations, they instituted tough initiation ceremonies. Journeymen in Bergen, Norway, were shoved down a chimney, thrown three times into the sea, and soundly whipped. Such rites made belonging to the guild or corporation more precious to those who were accepted, and survived.

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.