The usual answer to this question is "No," but that is not the right
answer. The purpose of the following remarks is to show that the
answer should be "Yes." I want to show that without any extraordinary
difficulty we can illustrate the theory of a finite universe by
means of a mental image to which, with some practice, we shall soon
grow accustomed.

First of all, an observation of epistemological nature. A
geometrical-physical theory as such is incapable of being directly
pictured, being merely a system of concepts. But these concepts
serve the purpose of bringing a multiplicity of real or imaginary
sensory experiences into connection in the mind. To "visualise"
a theory, or bring it home to one's mind, therefore means to give
a representation to that abundance of experiences for which the
theory supplies the schematic arrangement. In the present case we
have to ask ourselves how we can represent that relation of solid
bodies with respect to their reciprocal disposition (contact) which
corresponds to the theory of a finite universe. There is really
nothing new in what I have to say about this; but innumerable
questions addressed to me prove that the requirements of those who
thirst for knowledge of these matters have not yet been completely
satisfied.

So, will the initiated please pardon me, if part of what I shall
bring forward has long been known?

What do we wish to express when we say that our space is infinite?
Nothing more than that we might lay any number whatever of bodies
of equal sizes side by side without ever filling space. Suppose
that we are provided with a great many wooden cubes all of the