An expert is someone who knows some of the worst mistakes that can be made in his subject, and how to avoid them.

Qunntum theory provides us with a striking illustration of the fact that we can fully understand a connection though we can only speak of it in images and parables.

*Physics and Beyond * (New York 1971)

We will have to abandon the philosophy of Democritus and the concept of elementary particles. We should accept instead the concept of elementary symmetries.

Quoted in E Maor, *To infinity and beyond* (Princeton 1991)

Thus, the more precisely the position is determined, the less precisely the momentum is known, and conversely.

I think that modern physics has definitely decided in favor of Plato. In fact the smallest units of matter are not physical objects in the ordinary sense; they are forms, ideas which can be expressed unambiguously only in mathematical language.

The physicist may be satisfied when he has the mathematical scheme and knows how to use for the interpretation of the experiments. But he has to speak about his results also to non-physicists who will not be satisfied unless some explanation is given in plain language. Even for the physicist the description in plain language will be the criterion of the degree of understanding that has been reached.

*Physics and Philosophy*