Prince Karim, 88, was given the title of “His Highness” by Queen Elizabeth in July 1957, two weeks after his grandfather, the Aga Khan III, unexpectedly made him heir to the family’s 1,300-year dynasty as leader of the Ismaili Muslim sect.

The global Ismaili Muslim community witnessed a historic and deeply significant moment today as Shah Rahim Al-Hussaini, Aga Khan V, formally ascended to the office of Imamat as the 50th hereditary Imam of the Ismaili Muslims.

In his inaugural address, he “pledged to dedicate his life to care for the spiritual and material well-being of the Ismaili Jamat.”

Rahim Al-Hussaini was named Wednesday as the new Aga Khan, spiritual leader of the world’s millions of Ismaili Muslims, following the death of his father.

As leader of a branch of Shiite Islam, the Aga Khan mixed business projects and humanitarian initiatives as he built a personal fortune.

Canadian Prime Minister Justin Trudeau and Spain’s King Emeritus Juan Carlos were among the dignitaries who attended Saturday’s private ceremony for His Highness Prince Karim Al-Hussaini at the Ismaili community center. Portugal’s President Marcelo Rebelo de Sousa and the mayor of Lisbon were also among the mourners.

The Aga Khan IV was often referred to as a philanthropist, but the description ignores the spiritual impetus for his work.