The reign of Emperor Yongle, or 'Perpetual Happiness' - which began with civil war and a bloody coup, and saw the construction of the Forbidden City, completion of the Grand Canal, and consolidation of the imperial bureaucracy - was one of the most dramatic and significant in Chinese history. In 1368 Yongle's father, the Buddhist monk Zhu Yuanzhang, led the rebels who reclaimed China from the Mongol-ruled Yuan dynasty and reigned for 30 years as Emperor Hongwu, establishing the Ming dynasty. But Yongle (Zhu Di, 1360-1424) did not directly succeed his father; the throne first passed briefly to Yongle's nephew, Emperor Jianwen, whom Yongle drove from the palace (and possibly murdered) in 1402. The strong, centralised, autocratic government set up by his father and developed by Yongle - which concentrated power in the emperor, his eunuch assistants, and the scholar-advisors of the Grand Secretariat - lasted for more than two centuries. Yongle moved China's capital from Nanjing to Beijing in 1421, where he constructed the magnificent Forbidden City, in which twenty-three successive emperors would reside. He rebuilt the Grand Canal, directly linking the new capital to the fertile Yangzi Delta and facilitating grain shipments for Beijing's burgeoning population. He relentlessly pursued expansion of China's territory into Mongolia, Manchuria, and Vietnam, and sent the admiral Zheng He on six voyages - each employing more than sixty vessels - to Southeast Asia and the Indian Ocean, establishing contact with places as distant as Hormuz in the Persian Gulf and Somalia in Africa. As an expression of his wish to emulate the sage-kings of Chinese antiquity, Yongle sponsored numerous literary projects, the most ambitious of which was "The Grand Encyclopaedia of Yongle" (Yongle dadian), a compendium of 11,095 volumes on all fields of knowledge. Beginning with an hour-by-hour account of one day in Yongle's court, Shih-shan Henry Tsai presents the multiple dimensions of Yongle's life in fascinating detail. Tsai examines the role of birth, education, and tradition in moulding the emperor's personality and values, and paints a rich portrait of a man characterised by stark contrasts. Synthesising primary and secondary source materials, he has crafted a colourful biography that enhances our understanding of imperial China in general and the early Ming dynasty in particular. "Perpetual Happiness" will captivate all who enjoy historical biography, and will be of interest to specialists in history and Asian studies. Shih-shan Henry Tsai is professor of history and director of Asian studies at the University of Arkansas. He is the author of four books, including "Eunuchs in the Ming Dynasty".