The difference between the bahak of both types and the true white baras is that the bahak nests in the skin and, if it goes deep, it is very insignificant, while the baras penetrates the skin and meat to the bone. The common cause of all these diseases is the weakness of the changing force, which does not completely assimilate the nutrient substance, but in Bahaka the matter is more fluid and the expelling force is greater, and it drives the matter to the surface of the skin, whereas in Baras the matter is thick and the expelling force is therefore weak matter gets stuck inside and spoils the nature of the organs into which it penetrates, so that there is greater adhesion of the nutrient and there is no assimilation these concepts are already known to you from the section on forces.
When this matter is established there, it transforms the nourishment reaching it into its nature, even if it is the best nourishment, just as good nature transforms bad matter into good quality, or like plants, transplanted from one place to another, become poisonous edible or from edible poisonous. Galen and others say that a plant called labah bore poisonous fruits in Fars, and when it was transplanted into Egypt, its fruits were among the things eaten. Just as the color of animals and plants changes depending on the area, it is quite possible that matter also changes depending on the organs - after all, the latter are like a habitat for it. When the organ becomes slimy and its flesh becomes like the flesh of shells, it imparts its slimy nature and its white color to good blood. The difference between both bahaks is that one of them is caused by black gall matter, and the other comes from raw mucus.
As for the disease called black bara, its relationship to the white bara is not the same as the relationship of the black bara to the white bara, on the contrary, it is something different from the white bara in essence. The fact is that black sheep is the so-called scaly lichen, that is, a shingles that affects the skin with great roughness and scaliness, like in fish, accompanied by itching. The reason for this is black gall juice, which the skin absorbs from surrounding areas, and so much so that it affects not only its color, and such baras is the precursor of leprosy. Although this disease is malignant and, having become chronic, cannot be cured, like chronic bahak, it is still safer than white baras. The reasons for all this are well known.
Know that baras sometimes occurs after the use of cupping. It appears on the marks from them and multiplies there, since liquid is attracted along with the blood, and the blood does not accompany it when sucked out by the cups, and remains in the skin, and the wounded skin cannot fully carry out its actions.
As for the black bahak, its recognition is not difficult to distinguish the wadah, which is a white bahak, from the malignant baras. One of the differences between them is that on the vadaha the hair grows the same color as the hair on the head - black or blond, but on the baras only white hair grows, not otherwise. With baras, the skin on the sore spot is lower and more depressed than the skin on the rest of the body, sometimes this also happens with vadaha, but only very rarely. I will also say that blood comes out of a vadakh when pricked with a needle, but from a baras it is not blood, but a watery liquid, and such a baras cannot be cured. Another sign is if the place turns red from rubbing, then there is hope, and this is rather a bahak, and if the place does not turn red, this is bad.
As for the differences between black bahak and black baras, these are peeling, scalyness and shingling - this is not the case with black bahak. Further, black sheep are also heterogeneous sometimes they are rough, sometimes they are smooth. The smooth variety of both white spots is worse, and the smooth variety of both black spots is better, for it is bahak and not baras. Black sheep can be very far from the color of the body, and sometimes closer to it, and this is safer. If the baras is deepened, does not turn red and does not bleed, or it is very extensive and takes up a lot of space, then there is no hope, just as if it is increasing all the time, for this means that its nature is strong and it turns the adjacent tissues into something similar to itself . Therefore it is very malignant.