"We cannot build physics on the basis of the matter-
concept alone. But the division into matter and field
is, after the recognition of the equivalence of mass and
energy, something artificial and not clearly defined.
Could we not reject the concept of matter and build
a pure field physics? What impresses our senses as
matter is really a great concentration of energy into a
comparatively small space. We could regard matter as
the regions in space where the field is extremely strong."
from The Evolution of Physics
