science and against superstition and hypothetical
philosophy. The other contents of the Corpus are
older or later than this nucleus, either in harmony
with its doctrines or opposed to them. More than
this we cannot hope to know for certain.
3. Means of Dating Hippocratic Works
The means of fixing the dates of the treatises
composing the Hippocratic collection are twofold--external
and internal.
The external evidence consists of the statements
of Galen and other ancient authors.
The internal tests are :--
(a) The philosophical tenets stated or implied ;
(b) The medical doctrines ;
(c) The style of the treatise ;
(d) The language and grammar.
(a) When a philosophic doctrine is adopted, or
referred to as influential, it is presumptive evidence
that the treatise was written before that doctrine
grew out of date. We cannot, however, always be
sure when a doctrine did grow out of date. It is a
mistaken idea to suppose that the rise of a fresh
school meant the death of its predecessors. It is
certain, for instance, that Heraclitus had followers,
after the rise of other schools, who developed his
doctrines without altering their essential character.
(b) Medical doctrines also are by no means a
certain test. If we could be sure that a knowledge
