There are three constants in life... Change, Choice and Principles.

A blind person could make a lifelong study of the eye, properties of light, the sight process and become a great expert in the field, but in another sense he would know nothing about sight. A person could know a great deal about God and yet not know God.

The significant problems we face cannot be solved at the same level of thinking we were at when we created them - Einstein

Yet if there really were a complete unified theory, it would also presumably determine our actions—so the theory itself would determine the outcome of our search for it! And why should it determine that we come to the right conclusions from the evidence? Might it not equally well determine that we draw the wrong conclusion? Or no conclusion at all?

I have taken the opportunity to update the book and include new theoretical and observational results obtained since the book was first published (on April Fools' Day, 1988).

According to some accounts, a journalist told Eddington in the early 1920s that he had heard there were only three people in the world who understood general relativity. Eddington paused, then replied, "I am trying to think who the third person is.")

model-dependent realism. It is based on the idea that our brains interpret the input from our sensory organs by making a model of the world. When such a model is successful at explaining events, we tend to attribute to it, and to the elements and concepts that constitute it, the quality of reality or absolute truth.

The naive view of reality therefore is not compatible with modern physics. To deal with such paradoxes we shall adopt an approach that we call model-dependent realism. It is based on the idea that our brains interpret the input from our sensory organs by making a model of the world. When such a model is successful at explaining events, we tend to attribute to it, and to the elements and concepts that constitute it, the quality of reality or absolute truth.

Though realism may be a tempting viewpoint, as we'll see later, what we know about modern physics makes it a difficult one to defend.

I was lucky to lose my voice at the beginning of the personal computing age.

We are used to thinking of intelligent life as an inevitable consequence of evolution, but what if it isn't? The Anthropic Principle should warn us to be wary of such arguments. It is more likely that evolution is a random process, with intelligence as only one of a large number of possible outcomes.

This result was very convenient for Marxist—Leninist dialectical materialism