Cleverly seizing Oboi
Oboi, as regent minister, grew arrogant and domineering, formed cliques for private gain, and killed ministers at will. The sixteen-year-old Kangxi feigned an obsession with buku (wrestling) games, choosing a band of youth guards to practice daily. In 1669, when Oboi came alone to audience, the youths rushed him all at once and pinned him down. His thirty great crimes were listed, and in view of past service his life was spared but he was imprisoned. The coup moved not a single soldier — a "children’s game" under the power-minister’s very eyes carried out the recovery of power.
Learning geometry from the Jesuits
In the calendar dispute, Kangxi found that his officials understood neither Chinese nor Western methods, and resolved to master it himself: he summoned Jesuits such as Ferdinand Verbiest into the palace to teach Euclidean geometry and astronomical calculation, studied several hours a day for years on end, and personally computed eclipses and surveyed river courses. The mathematical terms in modern Chinese for "unknown," "power," and "root" are said to derive from Kangxi’s study notes. The window of an emperor studying Western learning never became state policy — the opportunity opened and closed in one man’s study.