Pope Francis on Saturday elevated 21 clergymen from all over the world to the rank of cardinal, saying that diversity is essential to the future of the Catholic Church.

The ceremony, known as a consistory, is the ninth since Francis was elected pope in 2013. It occurred in St Peter’s Square in Vatican City, with a crowd filling half of the square.

The new cardinals include diplomats, close advisers, and administrators from all over the world. Eighteen are under 80 and thus eligible to vote as “cardinal electors” in the next conclave, when Francis’ successor will be decided.

Francis said that the College of Cardinals is called to resemble a symphony orchestra, representing the harmony and synodality of the Church. 

He emphasized the importance of diversity, saying that each sound must contribute to the common design.

Among the new cardinals is Archbishop Stephen Chow of Hong Kong, who is seen as playing a key role in seeking to improve relations between the Vatican and Beijing. 

Another new cardinal is Archbishop Pierbattista Pizzaballa, the top Catholic authority in the Holy Land.

Francis has also appointed several top administrators in the Curia, the Holy See’s government, to the rank of cardinal.

This includes Claudio Gugerotti, the Italian prefect of the Dicastery for the Eastern Churches; Victor Manuel Fernandez, whom Francis recently named head of the powerful Dicastery for the Doctrine of the Faith; and Robert Prevost, a former missionary in Peru who leads the Dicastery for Bishops.