I studied economics and made it my career for two reasons. The subject was and is intellectually fascinating and challenging, particularly to someone with taste and talent for theoretical reasoning and quantitative analysis.

It was at this moment that I wrote my first important paper in theoretical physics. I was 32 years old, 5 years beyond the alleged age of senility for theorists.

The theoretical understanding of the world, which is the aim of philosophy, is not a matter of great practical importance to animals, or to savages, or even to most civilised men.

Practical knowledge of what works and what doesn't work is much better. Theoretical knowledge is important, but I think practical knowledge works better.

All the evidence, experimental and even a little theoretical, seems to indicate that it is the energy content which is involved in gravitation, and therefore, since matter and antimatter both represent positive energies, gravitation makes no distinction.

After some minor pieces of theoretical study that I worked on, a student in my statistical mechanics class brought to my attention a problem in polyelectrolytes.

After finishing the gymnasium in Muenchen with 9 years of Latin and 6 years of ancient Greek, history and philosophy, I decided to become a physicist. The great theoretical physicist Arnold Sommerfeld, an university colleague of my late father, advised me to begin with an apprenticeship in precision mechanics.

Einstein's gravitational theory, which is said to be the greatest single achievement of theoretical physics, resulted in beautiful relations connecting gravitational phenomena with the geometry of space; this was an exciting idea.

Mediocre theoretical physicists make no progress. They spend all their time understanding other people's progress.

The amount of detailed information which an individual has at his command and his theoretical elaborations of the same are mutually dependent; they grow in and through each other.

When friends and lovers die and your world gets quieter; that's when the silence comes closer; that's when next isn't the least bit theoretical or abstract.

I recognise that Socialism has ended its purely theoretical course, and that the hour to construct has come.

I do theoretical particle physics. We're trying to understand the most basic structure of matter. And the way you do that is you have to look at really small distances. And to get to small distances, you need high energies.

I want to study theoretical physics because it is one of the hardest things there is.

For me, playwriting is and has always been like making a chair. Your concerns are balance, form, timing, lights, space, music. If you don't have these essentials, you might as well be writing a theoretical essay, not a play.

Theoretical principals must sometimes give way for the sake of practical advantages.

Coaching courses are still much too theoretical, and this is what you see reflected in the basic technical skills of the average player. I even see things deteriorating.

If philosophy is practice, a demand to know the manner in which its history is to be studied is entailed: a theoretical attitude toward it becomes real only in the living appropriation of its contents from the texts.

A healthy economics has got to have both conceptual, theoretical research and applied, empirical research.

The methods of theoretical physics should be applicable to all those branches of thought in which the essential features are expressible with numbers.