Josiah's parents moved from Malawi to Zimbabwe in 1918. His father was a builder at Tengenenge, a large tobacco farm in those years. He made extra money for the family by carving masks. Taught by his father, Josiah also became a mask carver. He made his start with sculpting stone in 1967. During the morning he would work on the farm and in the afternoon he would sculpt.
When Tengenenge closed in 1979 because of the war, the Manzi family is the only one which stayed at Tengenenge. During this time period in Zimbabwe, there was a budding art movement in the making. It was relatively slow to develop but was given massive impetus in 1966 by the owner of Tengenenge, Tom Blomefield, a white South-African-born farmer. The farm had extensive deposits of serpentine stone suitable for carving. A sculptor in stone himself, he wanted to diversify the use of his land and welcomed Josiah and new sculptors onto it to form a community of working artists. This was in part because at that time there were international sanctions against Rhodesia's white government led by Ian Smith, who had declared Unilateral Declaration of Independence in 1965, and tobacco was no longer able to generate sufficient income. Appropriately, Tengenenge means 'The Beginning of the Beginning' - in this case of a significant new enterprise that has lasted through to the present day.
Josiah's work is spiritual, maybe because of his Yao culture. In some of his sculpture, the anatomy develops new and often disturbing relationships. To Josiah it seems natural for breasts to develop from thighs, yet to the on looker it seems surreal and a subversion of orthodoxy. His 'Monkey and Owl and his Mirror' seen like giant cameos-the smooth, carved figures of the animals, the bird and the human face carefully inlaid into the stone and offset by their natural setting. He notes, "Before I start a sculpture, I take off the blanket of stone, like taking off the skin of an animal. Nobody eats an animal before the skin is taken off".
The list of Josiah's accomplishments is extensive and spans decades. He is still carving at 81 years old and married to the sculptress Janet Manzi with seven children.