e the trial himself, Boyle
withholds judgment, even though the material came from a "very
experienced" gentleman. Or again, he talks about "sober travelers" who
made certain claims regarding the treatment of poisons. But, he says,
"having not yet made any trial of this my self, I dare not build upon
it."[53]

There are numerous such instances, scattered throughout his works, where
he reports an alleged cure but specifically indicates his own mental
reservations. Clearly, he is quite cautious in accepting the statements
of others, even though they were "sober" or "experienced" or even
"judicious." On the other hand, he is extremely uncritical when he
himself uses the term "cure" and when he attributes cures to particular
medicines.

His skepticism he indicates in references, for example, to Paracelsus
and van Helmont. Their specific remedy against "the stone," he says, and
their claims that they can reduce stones to "insipid water, is so
strange (not to say incredible) that their followers must pardon me, if
I be not forward to believe such unlikely things, til sufficient
experience hath convinced me of their truth."[54] Here, of course, we
see further a feature of critical acumen. A claim is made, but if this
claim runs counter to Boyle's own accepted body of knowledge, or to
logical doctrines derived from other directions, mere assertion cannot
carry conviction. "Sufficient experience" must play its part, and just
what constitutes "sufficient" we are not quite sure.

In judging the effectiveness of a remedy or the credibility of a
statement, one of the most important weapons was _analogy_. Direct
observation of a phenomenon was good. Next best was direct observation
of some _analogous_ phenomenon whereby one body acted upon another to
alter its properties or induce significant changes. Boyle drew his
analogies largely from chemistry, but he had no hesitation in applying
them to medicine.

Claims that medicines swallowed by mouth could dissolve stones in the
bladder seemed a priori unlikely. Yet there was considerable authority
that this took place; many persons had reported that this was a _fact_.
Boyle kept an open mind. He might be highly skeptical in regard to the
claims for any particular medication, but he did not deny the principle
involved. The possibility that some fluid, when swallowed, could have a
particular specific action on stones in the bladder, without affecting
the rest of the body, he considered