In his Romanes Lecture ¹ Oliver Lodge said: "The
mass which is explicable electrically is to a considerable
extent understood, but the mass which is merely
material (whatever that may mean) is not understood
at all. We know more about electricity than about
matter; . . . It is possible, but to me very unlikely,
that the electron as we know it contains a material
nucleus in addition to its charge." Verily a Berkeley
come to judgement! Now I am neither minded nor
competent to review modern discussions of matter, but
their general trend is perfectly clear to everyone. The
most advanced and competent physicists ² to-day do
not believe for an instant in the microscopic tennis-ball,
the minute atom of matter which was supposed to be
the bearer of natural phenomena. The conceptions of
the 'underlying' or 'ultimate' entity are very diverse;
we hear now that it is a mass, now an energy unit, now
a mathematical point, and again an electric charge or
electron. While the notion of an ultimate material
substance is as definitely renounced as ever Berkeley
desired it to be. According to the definition of Bosco-
vich, the physical atom is a "geometrical point in space,
a sizeless centre of force, having position, inertia and
rigidity." The reader may decide what one of these is a
physical substance. Somewhat similarly Ostwald ³ has

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