As Mother Teresa's birth centenary celebrations commenced here on Thursday, Pope Benedict XVI has sent a message to the Missionaries of Charity, joining “spiritually” in the celebrations and giving the order and the people they serve his blessings.

In a letter to Superior-General of the Missionaries of Charity Sister Prema, Pope Benedict said: “This year will be for the Church and the world an occasion of joyful gratitude to God for the inestimable gift that Mother Teresa was in her lifetime.”

Pope Benedict said Mother Teresa exemplified the words of Saint John: “Beloved, if God so loves us, we ought also to love one another. If we love one another, God abides in us and his love is perfected in us.”

Expressing the hope that this love would continue to inspire the Missionaries of Charity in their work, the Pope said: “I encourage you to draw constantly from the spirituality and example of Mother Teresa.”

The letter was read out at a special mass held at Mother House, headquarters of the Missionaries of Charity, by Archbishop of Calcutta Rev. Lucas Sirkar.

“Today people from all nations, castes, creeds and walks of life celebrate God's love and light, which radiated on our cold and darkened world through Mother Teresa,” Sister Prema said.

A stream of visitors came in to pay homage to Mother Teresa at Mother House all through the day.

Railway Minister Mamata Banerjee inaugurated ‘Mother Express,' an exhibition train with photographs depicting the life and philanthropic deeds of Mother Teresa, at the Sealdah Station.

At the inauguration, Sister Prema spoke about the close association Mother Teresa had with the Railways. It was on a train she took from the same station to Darjeeling when Mother Teresa received what she herself described as “the call within a call” — the moment when she received a message from God to leave the convent were she was a nun and begin her work in the slums of Kolkata.

When several other centres of the Missionaries of Charity came up in other cities, she would often travel to them, but always in third class and without reservation. “Mother liked to travel like the poor and among the poor,” Sister Prema said.

Ms. Banerjee said she had spoken to Prime Minister Manmohan Singh, Congress president Sonia Gandhi and Finance Minister Pranab Mukherjee, urging them to ensure that the Government of India observed the centenary year in a befitting manner.

A Mother Teresa International Film Festival 2010 was also inaugurated.