Book 2
9
Now Nature has made no organ for clearing away phlegm, this being cold and moist, and, as it were, half-digested nutriment; such a substance, therefore, does not need to be evacuated, but remains in the body and undergoes alteration there. And perhaps one cannot properly give the name of phlegm to the surplus-substance which runs down from the brain,cf. p. 90, note 1. Ther term catarrh refers to this running down, which was supposed to take place through the pores of the cribriform plate of the ethmoid into the nose. but one should call it mucus [blenna] or coryza — as, in fact, it is actually termed; in any case it will be pointed out, in the treatise On the Use of Parts, how Nature has provided for the evacuation of this substance. Further, the device provided by Nature which ensures that the phlegm which forms in the stomach and intestines may be evacuated in the most rapid and effective way possible — this also will be described in that commentary. As to that portion of the phlegm which is carried in the veins, seeing that this is of service to the animal, it requires no evacuation. Here too, then, we must pay attention and recognise that, just as in the case of each of the two kinds of bile, there is one part which is useful to the animal and in accordance with its nature, while the other part is useless and contrary to nature, so also is it with the phlegm; such of it as is sweet is useful to the animal and according to nature, while, as to such of it as has become bitter or salt, that part which is bitter is completely undigested, while that part which is salt has undergone putrefaction. And the term complete indigestion refers of course to the second digestion — that which takes place in the veins; it is not a failure of the first digestion — that in the alimentary canal — for it would not have become a humour at the outset if it had escaped this digestion also.
