has been manifested throughout the whole course of our
experience. Even our own self-consciousness involves the
consciousness of ourselves as partly material bodies. These
considerations show that our hypothesis is very different from
the ordinary hypotheses with which science deals. The entire
absence of testimony does not raise a negative presumption except
in cases where testimony is accessible. In the hypotheses with
which scientific men are occupied, testimony is always
accessible; and if we do not find any, the presumption is raised
that there is none. When Dr. Bastian tells us that he has found
living organisms to be generated in sealed flasks from which all
living germs had been excluded, we demand the evidence for his
assertion. The testimony of facts is in this case hard to elicit,
and only skilful reasoners can properly estimate its worth. But
still it is all accessible. With more or less labour it can be
got at; and if we find that Dr. Bastian has produced no evidence
save such as may equally well receive a different interpretation
from that which he has given it, we rightly feel that a strong
presumption has been raised against his hypothesis. It is a case
in which we are entitled to expect to find the favouring facts if
there are any, and so long as we do not find such, we are
justified in doubting their existence. So when our authors
propound the hypothesis of an unseen universe consisting of
phenomena which occur in the interstellar ether, or even in some
primordial fluid with which the ether has physical relations, we
are entitled to demand their proofs. It is not enough to tell us
that we cannot disprove such a theory. The burden of proof lies
with them. The interstellar ether is something concerning the
physical properties of which we have some knowledge; and surely,
if all the things are going on which they suppose in a medium so