The Archbishop of Canterbury has described Archbishop Desmond Tutu as a "towering spiritual figure" following a meeting between the two leaders in London on Wednesday.
Tutu was in London to receive the Templeton Prize for his contribution to "affirming life's spiritual dimension".
Archbishop Justin Welby said the world owed "an enormous debt of gratitude" to Tutu and that it would be hard to imagine South Africa today without "the unrelenting presence and prayers of this towering spiritual figure".
"Like few others, Archbishop Tutu incarnates the grace of God – surviving decades of unthinkable trials and torment, he somehow did not forget how to dance or sing," he said.
"More recently his name has become synonymous with the courage to face truth and the pursuit of reconciliation. I thank God for this life of inspiration and witness."
Tutu was presented with the Templeton Prize at a ceremony in London on Tuesday.
He spoke of the African concept of "ubuntu", in which a person can only be a person through co-existence with other people.
"You can be generous only because you learned from another how to be generous. How God longs for us to know that we were created for togetherness," he said.
"We were created to be members of one family, God's family, the human family."