Against Those Who Have Written on Disease Patterns

​These things having already been written, and having been distributed to some of the companions, or others having demanded to learn how it stands with the diagram, I immediately answer to those who pose the questions the multitude of the types. Therefore, the method is not of some other kind, but subordinate to the former one. And you yourself will be convinced that it is so, if you first recall and always keep handily in your memory of them, that in this context we call “day” the time composed of both day and night, which some address as a “nychthemeron” (night-and-day). In this way, at any rate, we also say that the year is of three hundred and sixty-five days and a quarter. Thus, of one day there are twenty-four hours, and of two, forty-eight, and of three, seventy-two; but the names for the types are not from the completed days, but from the recurrence of the paroxysm. For we call “tertian” that in which the paroxysm occurs every third day, with two days clearly having been completed in between; and “quartan” that in which it occurs on the fourth day, with three days completed in between in addition to this; and analogously for the others; so that when you find a period of a type to be of four days, you will call it a “quintan”, for it is not the same thing to have paroxysms every fifth day and to have a period of five days. Having put these things, therefore, in your memory, recall for me again the method mentioned before regarding the diagram. And it was said that you should examine whether the presented number of periodic hours, which is the paroxysm that occurs between two beginnings, measures any number contained in the diagram. And those [numbers] had arisen according to the multiplication of twenty-four hours. Therefore, in order that you yourself may find this on your fingers without a diagram, do these things. When six and eight are presented, you would easily find that four quotidian [fevers] arise when the presented period is of six hours, and three when it is of eight. But when seven is presented, or any other of those which do not measure the number of twenty-four hours, examine whether the presented [number] has any part (divisor), or none except for the unit. If indeed it has some other part besides the unit—just as nine has a third, and fifteen a third and a fifth—examine which of its parts is common to that of twenty-four. Immediately, at any rate, the number of twenty-four hours has a third, but it does not have a fifth, as that of fifteen [does]. If, then, the presented period happens to be of nine hours, you will take the third of this, and the third of twenty-four, which is eight, and you will say that there are eight types circumscribed by three days. And I requested you to remember that such types are called “quartans”. And if the period is of fifteen hours, taking the third of fifteen, you will say that the types are of five days, which is “sextans”; and since the third of twenty-four is also eight, you will say that there are also this many sextan types; and if the presented number has no part [in common], just as seven is, there will be twenty-four “octans”.