What's this sculpture about?
That is a Nkisi Nkondi (a Power Figure) from the Democratic Republic of the Congo....
One artist carves the piece and a diviner (ritual expert) would put a secret formula of ingredients into the cavities in the belly and the back of the figure. The mirror obscures our ability to see within the cavity and the reason for that is because only the diviner who fills it knows what is inside. Its also believed to be porous so that the forces contained inside can emanate out. The community can ask or tell the spirit of the ancestor to aid them in various situations.
For example, if there is a confrontation in the community, important members of the community come to together with those in conflict before the figure. The nganga (the person responsible for keeping the judicial harmony of the community) then places a nail or blade into the body of the figure to invoke or provoke the ancestor's spirit. Some describe the nails almost like a binding agreement, or promise.
If you look closely, you can see how each of the nails are different - some are very old and handmade and some are new and machine-made. The nails are indicative of changes in the market, a larger sociopolitical environment of the time (the presence of Belgian colonials and access to manufactured goods). You can read the history of the object through the evidence of it's use through time. It is quite a powerful piece. Also, the figure's pose, with hands on hips and head turned up, symbolizes its readiness to defend the righteous and to destroy enemies.
Why are the nails in the figure different shapes?
The nails are different shapes and sizes. Some are manufactured and machine made, and others appear to be hand made. This actually reflects how the object was used, and that it was used by a community over time. The nails are also indicative of changes in the market, a larger sociopolitical environment of the time (the presence of Belgian colonials and access to manufactured goods). This was a figure that was used within the community by a diviner (ritual expert) as this figure embodied the power or spirit of an ancestor. It could be used to resolve conflicts within the community; an agreement would be made and the nail pounded into the power figure by the nganga (who was responsible for keeping the judicial harmony of the community) functioned as a way to invoke the spirit - like releasing the power of the spirit - to bind the agreement.
Specifically, the power figure was an object that was used within a community and each of the nails would have been placed in the body of the power figure by the nganga ( the person who was responsible for keeping the judicial harmony of the community). The nganga could recall which nail was associated with which invocation. The nails were placed in the body to release the power of the ancestor. It was believed that the object was imbued with the spirit and power of an ancestor.
Scholarship focused on the Power Figure are theories since it is longer used. Some scholars have suggested that long, iron, round, or square nails may have been used for more serious crimes such as murder or to seal an argument with a solemn vow. Rectangular blades may represent less serious crimes. Blades with flared heads may have been believed to have power to kill supernaturally, and other items like screws were used for other types of conflicts. Some nails have rags or hair wrapped around them so that the nganga (who was responsible for keeping the judicial harmony of the community) could recall which nail was associated with which invocation.
Why are there nails in it?
This is a power figure made by a Kongo artist. These figures are meant to serve communities, helping to fight evil forces and offer protection. Each time a nail is driven into the figure, the figure is activated and called forth to help. Judging from how many nails and blades are here, this figure has done a lot of helping.
These works are actually "made" by several different people. There is a professional woodcarver who carves it, and later a nganga (a ritual expert) places spiritually powerful materials in the belly of the figure to give them power.