By Oana Lungescu
BBC News, Warsaw
The Kaczynskis used to worship at St Stanislaw Kostka church in Warsaw
In the spring sunshine, sirens and bells marked the two minute silence at midday across Poland. At the church of St Stanislaw Kostka in a suburb of Warsaw, the silence was particularly poignant.
Father Jerzy Popielusko, the chaplain of the Solidarity trade union who was murdered by the former communist secret police, is buried here.
And it was here that Lech Kaczynski and his wife Maria used to come to Sunday service.
Their pews were kept empty today, draped in a huge red-and-white Polish flag and a black ribbon.
The smiling pictures of the president and his wife were placed in front of the altar, together with the names of the other 94 people who died on board the presidential jet in Smolensk.
Young children gathered around, eagerly putting their hands up when the priest asked them why Poland was in mourning.
Outside the packed church, a group of elderly people wiped their tears.
'Distinct, not divisive'
A former Solidarity activist sobbed as she showed me a medal pinned to her black winter coat.
"I received it this last Wednesday from the head of the president's office, and now he's dead too," Danuta Kaniewska said.
"We've lost our elite. We're all in pain."
The signs of mourning are everywhere.
Polish flags and black ribbons hang from balconies and windows, outside banks, cafes and shops, on police cars and taxis.
Mr Fogelman remembers Lech Kaczynski as a man of values
For Lejb Fogelman, an international lawyer who has known Lech Kaczysnki and his twin brother Jaroslaw for 50 years, this is a personal loss.
He calls the dead president by his diminutive, Leszek.
They went to school together, striking a close but unusual friendship.
"I was a Jewish boy from a small town," he told me in his book-lined living-room. "They were very patriotic and Catholic."
It was from the Kaczynski twins that young Lejb heard the name Katyn - the 1940 Soviet massacre of more than 20,000 Poles - mentioned for the first time in school.
"The history of Katyn was hidden, it wasn't taught," he said.
"The communist powers didn't want to teach about the Soviet crimes, but to the twins it was an extremely important event. I remember that some boys were doubting it and we almost had a fight."
One of Lech Kaczynski's major ambitions, Mr Fogelman explained, was that "the world should recognise the harm done to Poland".
To many outside the country, in Russia and the rest of the European Union, Mr Kaczynski was a divisive figure. But that's not how his old friend remembers him.
"I see him not as a divisive, but a very distinct figure, a person who tried to preserve certain values in a world which tries to forget about them," he said.
Outside the presidential palace, young people are singing.
Late into the night, Poles young and old have come to light candles and lay flowers.
One of them was Tomasz, a law student, who at 21 is as old as Poland's democracy.
He did not share most of Lech Kaczynski's political views. But he cried in his bed when he heard the news of the plane crash on Saturday morning.
And today, he is in mourning for what Poles call their second Katyn.
Witold Liliental, 71, visited Katyn forest for the first time last Wednesday.
His father Antoni, a Polish reserve officer, was 31 when he was killed by the Soviet secret police. His son was barely one year old.
Mr Liliental, who now lives in Canada, travelled with the Polish Prime Minister Donald Tusk, but they flew on the same plane that crashed on Sunday.
"I did have some kind of a psychological discomfort because people have been talking for years that this plane is obsolete," said Mr Liliental.
Like many in Poland, he had heard rumours that the president himself may have ordered the pilots to land in Smolensk despite the thick fog - something he had done three years ago, when he insisted his jet should land in Georgia despite the war. But that is only speculation.
At a time of deep national trauma, Mr Liliental sees some signs of hope.
In Katyn last week, a young Russian journalist shook his hand and told him in Polish: "I am sorry, I apologise for Katyn."
"This was something wonderful," Mr Liliental said. And since then, like many Poles, he was moved by Russian Prime Minister Vladimir Putin's embrace of his Polish colleague at the site of the crash, a gesture which could strengthen a historic reconciliation between two nations which have long viewed each other with suspicion.
"We've gone a very long way," said Mr Liliental. "And there's something else that's good. Until now, many people had never heard about Katyn.
"Since this tragedy, people begin to know about Katyn. Maybe these people did not die in vain."