Another Mpongwe trade medicine is Mbumbu (which means "rainbow"). Old tradition said that the rainbow was caused by a forest vine which a great snake had changed to the form of the sun-colored arc. The seeker of wealth is aided by the doctor to obtain a piece of this rainbow, which he keeps in secret, and can carry hidden with him. By it he is able at any time to kill any one of his relatives whom he may choose (of course unknown to them) and send their spirits off to induce foreign traders to give him a store of goods (the children's pot of gold at the rainbow's end?).
_For Sickness._ Among the Mpongwe and adjacent tribes there are three kinds of spirits invoked, according to the character of the disease. These are Nkinda, Ombwiri, and Olâgâ.
It is clear that these, as explained in a previous chapter, are names of spirits, but the same names (as in the case of other fetich mixtures) are given to the medicines in whose preparation they are invoked. But my informants differed in their opinions whether these names indicate different kinds of spirits, or only a difference in the functions or works done by them. One very intelligent and prominent native at first seemed uncertain, but subsequently said that "Nkinda" indicated the spirits of the common dead; "Ombwiri" the spirits of distinguished dead, kings, and other prominent men; and "Olâgâ," a higher class, who had been admitted to an "angelic" position in the spirit-world. All, however, asserted that all these are spirits of former human beings. Which kind shall be invoked depends on the doctor's diagnosis of the disease.
[Illustration: NATIVES TRADING IN PLANTAINS AND BAMBOO BUILDING MATERIALS.--GABUN.]
Take the case of some one who has been sick with an obscure disease that has not yielded to ordinary medication: the doctor begins his incantations with drum and dance and song. This is sometimes kept up all night, and in minor cases the patient is required to join in these ceremonies. But in the more mystic Nkinda, Ombwiri, and Olâgâ the sick person sits still, being required to do so as a part of the diagnosis. For if after a while the patient shall begin to nod his head violently, it is a sign that a spirit of some one of these three classes has taken possession of him. The doctor then takes him to a secret place in the forest, and asks the spirit what kind it is, and what the nature of the disease. The reply, though made by the patient, is not supposed to be his, but the spirit's who is using his mouth. Really the sick, dazed, submissive patient does not know what he is saying. After this diagnosis the doctor goes to seek plants suitable for the disease. By chance the patient may recover. If he does not, the doctor asserts that the spirit had misinformed him, and the ceremony must be performed again.