Johnson, to Boswell: "Sir, to leave things out of a book,
merely because people tell you they will not be believed, is
meanness."

ONE of the oldest dilemmas of philosophy
is that between continuity and discontinu-
ity, involving also the much discussed question
of action at a distance. I believe it was Carlyle
who, granting that matter acts only where it is,
asked, "But where the devil is it?" Where mat-
ter is and where it acts, and whether it is to be
regarded as a continuum or a discontinuum,
are questions concerning which the scientific
mind has changed in recent years, and probably
will change still further in the near future.

Although the idea that matter might be com-
posed of indivisible particles had long been cur-
rent in philosophy and in common speech, phys-
ics and chemistry up to the time of Dalton had
been developed in terms of the continuum. In-
deed, it is within our own lifetime that the atom
and the molecule, from being mere working
hypotheses, have come into a high degree of
reality. Yet even now if it is asked whether the

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