Mother Teresa, who died in Kolkata, India, 19 years ago, will be formally declared a Saint of the Catholic Church by Pope Francis at a Vatican ceremony on Sunday. David Willey, who has reported from Rome for the BBC during five decades, tells how he once spent an hour sitting and talking informally with the new saint in an unlikely setting, the arrivals hall at Rome's Fiumicino airport.
I immediately understood that the woman already known as the "Saint of the Slums" of Kolkata was at the same time a very humble and simple caring person and a sophisticated international traveller.
She constantly jetted around the world, visiting her Missionaries of Charity, the religious order she had founded in 1950, so I suppose it was appropriate that we should meet, not in her motherhouse near the Coliseum in Rome, or in one of her hospices for the dying in India, but amid the bustle of an airport.
We sat together in the arrivals section and she quickly had me laughing as she proudly showed off her Air India travel pass, which entitled her to a lifetime of free worldwide air travel - a gift of the Indian government.
I had been trying to arrange an interview with her for months, but the nuns at her Rome headquarters kept putting me off. Finally they rang me to say she would be arriving on such-and-such a flight from India and departing an hour-and-a-half later to Canada and I could meet her for a brief talk at the airport.
She was a tiny figure and her face was already rather wizened. She was immediately recognisable as she emerged alone through the arrival doors clutching a small white cloth bag, dressed in the blue-trimmed white cotton Indian sari and veil which she had adopted as the uniform dress for members of her missionary order.
"Do you have to pick up your suitcase as you are in transit?" I asked, feeling slightly foolish for suggesting that a living saint might misplace her baggage tag.
"No," she replied. "I carry around all my worldly possessions with me in this little bag. My personal needs are very simple!"
Before tackling more weighty metaphysical and theological matters and hearing how she devoted her life to the poorest of the poor, I decided to try to find out more about how a living saint organises her travels. I was intrigued by her Air India free travel pass.
"How do you plan ahead?" I asked, in the pre-mobile phone era.
"Well I usually ring up, from a coin box at the airport, the head of state or the prime minister or Pope John Paul at the Vatican if I am in Rome - and they send a car to the airport to meet me," she said.
By the time I met her in the late 1980s, Mother Teresa's sisters and affiliated brothers and fathers had already grown to become an international family of 1,800 nuns and many thousands of lay workers.
Today they number nearly 6,000 and are active in 139 countries. Her order knows practically no territorial boundaries and she was already setting up homes and hospices and recruiting in Eastern Europe long before the fall of the Berlin Wall and the end of the Soviet Union.
She opened two centres in Hong Kong as early as 1983, but China has so far resisted attempts by the order to minister to their poor.
As the minutes ticked by, Mother Teresa went on to explain to me her single-minded devotion to her work of ministering to the sick, the dying and the disabled.
In her own words: "Our mission was to care for the hungry, the naked, the homeless, the crippled, the blind, the lepers, all those people who feel unwanted, unloved, uncared for throughout society, people that have become a burden to society and are shunned by everyone."
Pope John Paul II had visited Mother Teresa's hospice for the dying in Kolkata during his pilgrimage to India in 1986 and the two became close friends.
Mother Teresa frequently appeared at Vatican ceremonies at the Pope's side until her death. Later, in record time, in 2003 she was herself created a Blessed of the Roman Catholic Church, marking her final step towards full sainthood.
Her flight to Toronto was called and we walked together to the departures hall. She disappeared behind the automatic doors, still clutching her small cloth bag and passing unrecognised, it seemed to me, among the throngs of passengers criss-crossing the transit zone.
I knew I had met a living saint; she had touched my heart, transmitted her sense of joy for life, and she had also made me laugh.