Puhi-o-Aotea Ratahi was the third president of the Ratana church. She was born Erina Wiremu Ratana, probably in 1898 or 1899, at Orakeinui, which in later years became the Ratana pa settlement. Her father, Wiremu Ratana, had connections to Ngati Apa, Ngati Raukawa and Nga Wairiki. Her mother, Ihipera Koria Erina, was a Methodist of Ngati Hine descent. Both parents were descendants of the Taranaki tribes Nga Rauru and Ngati Ruanui. Her paternal grandfather was the Ngati Apa and Ngati Raukawa chief Ngahina Ratana. Little is known of Erina's early life. When she was 19 she married Panau te Mihaia Tamati, of Rangitane descent, at Parewanui. They lived at Rangiotu.
The origins of the movement which, in 1925, was to become the Ratana church, lay in the spiritual experiences of Erina’s elder brother, Tahupotiki Wiremu Ratana, in 1918. Erina supported her brother’s work, and from the 1920s at times travelled about the country with Ratana and his attendants, spreading their message of spiritual enlightenment to the Maori people. Puhi-o-Aotea was the spiritual name given to her by her brother.
Panau Tamati died in 1927, leaving her with four young children; one child had died two years earlier. On 23 January 1940, at Wanganui, she married Epiha Ratahi, a staunch follower of the Ratana faith; they had a daughter and also raised a grandson.
Puhi-o-Aotea Ratahi remained active in the movement after her brother’s death in 1939. In 1941 she unveiled and blessed the cornerstone of the refurbished Ratana temple. She succeeded her nephew, Matiu Ratana, as president of the movement in 1950. In 1955 she approved a reformulation of the church’s doctrines, which no longer mentioned the Mangai (T. W. Ratana) in the same phrase as the Holy Trinity. It was a time when Maori were coming to terms with the modern era of technology and urbanisation, and her work for the church was linked to her close interest in the welfare of Maori. She supported the advancement of the morehu, as Ratana’s followers were known, and Maori as a whole, through education, becoming a life member of the Maori Education Foundation in August 1961. Despite controversy aroused among morehu, Ratahi endorsed a book written about Ratana by J. McLeod Henderson in 1963. She acknowledged that in the past it had been church policy ‘not to publicise its teachings’, which had been orally given in the Maori language. However, her intention was to provide a means whereby the younger generation, especially morehu, might gain a ‘better understanding of the wonderful power and achievement of our Founder’.
Ratahi travelled about the country to support and encourage Ratana followers. In 1959 she was the patron of the reconstruction committee for Te Omeka, the settlement that Ratana established at Te Poi, near Matamata. In 1965 she led the first national tour made by a president of the church since the time of Ratana himself, and led a pilgrimage to Te Rere-o-Kapuni, the sacred stream of Mt Taranaki where Ratana had heard prophetic voices.
Puhi-o-Aotea Ratahi died suddenly at Ratana pa on 17 April 1966. Her tangihanga lasted for a week, during which thousands of mourners, including morehu and dignitaries, paid tribute. She was buried at the Piki-te-Ora cemetery at Ratana pa. In 1969 a trophy commemorating her was presented to the Ratana youth movement.