Although he had held high office, Mr S R Nathan remained down-to-earth.

Mr Chan Chun Sing, Minister in the Prime Minister's Office, recounted in Mandarin an incident that he said exemplified that.

Mr Chan, in 2011, had just become Acting Minister for Community Development, Youth and Sports, and Mr Nathan wanted to call on him at his office.

"I felt it was not right, and not proper etiquette, for him to visit me," said Mr Chan.

Instead, he went to meet the former president, whom he saw as his mentor, at his Ceylon Road home.

At the meeting, Mr Nathan explained to Mr Chan that he was no longer the president and just an ordinary citizen, now that he had retired.

So he felt that it was only right, as a matter of protocol, for him to call on Mr Chan, who was a minister.

Describing the incident, Mr Chan said: "Having heard what he said, I grew even more respectful of him... I learnt yet another important lesson from Mr Nathan - his humility and his magnanimity of spirit to help the younger generation is something that we should learn."