The actual science of the Hippocratic school was of course very limited.
It is doubtful whether the treatise in which this theory is fully expounded is as old as Hippocrates himself; but it was regarded as a Hippocratic doctrine, and, when taken up and expanded by Galen, its terms not only became the common property of the profession, but passed into general literature and common language.
The work of Celsus is thus for us only second in importance to the Hippocratic writings and the works of Galen; but it is valuable rather as a part of the history of medicine than as the subject of that history.
But they often show much practical experience, and exhibit the naturalistic method of the Hippocratic school.
In the other non-Hippocratic writings Ermerins thinks he can distinguish the hands of no fewer than nineteen different authors, most of them anonymous, and some of them very late.