78 Hippocratic Corpus and Diocles of Carystus
have the same powers, are mistaken; for it can be shown that from
[substances] that are similar in these respects, many dissimilar [effects]
result; ( 6 ) and indeed, one should also not suppose that every [substance]
that is laxative or promotes urine or has some other power is like that for
the reason that it is hot or cold or salt, seeing that not all [substances] that
are sweet or pungent or salt or those having any other [quality] of this
kind have the same powers; ( 7 ) rather must one think that the whole
nature is the cause of whatever normally results from each of them; for
in this way one will least fail to hit the truth.
( 8 ) Those who believe that with every single [substance] one should
state a cause why each one of such [substances] is nutritious or laxative or
promotes urine or has some other similar power, apparently do not know,
first, that for the use [of these substances] something like that is not often
necessary, and further, that many of the [things] that are [the case] in
some way look like some sort of starting-points by [their] nature, so that
they do not admit of the [kind of ] account that deals with [their] cause.
( 9 ) In addition, they sometimes make mistakes when, while accepting
[things] that are not known or are disputed or implausible, they think
that they state the cause sufficiently. ( 10 ) Therefore, one should not pay
attention to those who state causes in this way or to those who believe
that one should state a cause for all [things]; rather, one should give
credence to the [things] that have been well grasped on the basis of
experience over a long time. ( 11 ) One should look for a cause [only] of
the [things] admitting one, whenever it is by this that what is said turns
out to be better known or more reliable.’
( 12 ) These are the words of Diocles, who believes that the powers contained
in foodstuffs are known on the basis of experience only and not on the
basis of an indication according to mixture or an indication according to
humours. ( 13 ) There is still another [form of indication], namely the one
according to the parts of plants, but he did not mention this. ( 14 )By
indication according to the parts of plants I mean the one used in addition
to the others by Mnesitheus in his demonstration that powers in the roots
of plants are different from those in the stems, just as those in the leaves
are different, and those in the fruits, and those in the seeds.
It is important to note that both in the introduction to the fragment
and immediately after the verbatim quotation Diocles’ view is presented
by Galen as advancing anexclusivelyempirical approach to the question of
the powers of foodstuffs (section 2 : ‘through experience only’,
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