I'm not afraid of death, but I'm in no hurry to die. I have so much I want to do first.

A model is a good model if first it interprets a wide range of observations in terms of a simple and elegant model, and second if the model makes definite predictions that can be tested, and possibly falsified, by observation.

As we shall see, the concept of time has no meaning before the beginning of the universe. This was first pointed out by St. Augustine. When asked: What did God do before he created the universe? Augustine didn't reply: He was preparing Hell for people who asked such questions. Instead, he said that time was a property of the universe that God created, and that time did not exist before the beginning of the universe.

A zero-gravity flight is a first step toward space travel.

To understand recursion, one must first understand recursion.

My first popular book, 'A Brief History of Time,' aroused a great deal of interest, but many found it difficult to understand.