"If you had a problem - with life, with marriage, with something in the house - he would come at once," recalls Krzysztof Wierzbicki. "He loved to make things or repair machines and he was ambitious about it. If you said to him: `Krzysztof, help me because it's very difficult and I'm not very good at this kind of thing', he would try so hard to make it work to show you it wasn't so difficult."
Wierzbicki worked as Kieslowski's assistant on his early documentary films and later directed I'm So-So, the definitive documentary about him, which is to be screened for the first time in Britain this weekend as part of a short festival dedicated to the late Polish director.
Patently, Wierzbicki still misses his friend, and has a wealth of stories attesting to his humanity, humour and his surprising skills. He remembers the film-maker, who died three years ago this week, as a devoted family man, a passionate smoker and a skilful stunt driver who delighted in sudden, perfect 180-degree turns. He even testifies to Kieslowski's Dr Dolittle-like rapport with animals. "The wildest beasts became calm and happy when Krzysztof made friends with them," he recalls. "There was a warmth in him animals could feel. He could put his hand in the mouth of the most dangerous dog and nothing would happen."
In 1995, Wierzbicki inadvertently became the keeper of Kieslowski's last film testament when he made I'm So-So for Danish television.
In the film, Kieslowski talks elliptically and with characteristic intelligence about his career and beliefs. The film's title is taken from the director's laconic observation: "When Americans ask me `How are you?' I say `I'm so-so.' They immediately think something tragic has happened. You can't say `so-so'. You have to say `Well' or `Very well'. The most optimistic thing I can say is `I'm still alive'."
"I wanted to show what Krzysztof was like as a person," says Wierzbicki. "In Poland, the media image of him at that time was that he was a very sad, even unpleasant man. Journalists used to say he was cold because he sometimes answered stupid questions: `yes', `no' and `if you think so'. In my film, we showed the atmosphere that he made. For the first time, an audience could see him smile."
As a director, Kieslowski came to loathe the exhausting business of filming. He regarded editing as the key creative process and worked with extraordinary dedication in the cutting-room. For The Double Life of Veronique, for example, he edited more than 20 separate versions before eventually coming up with the innovative structure of the final film.
After Red, Kieslowski announced that he was finished with film-making, and retired. Many critics now believe that, had he lived, he would eventually have returned to directing, perhaps of scripts for a new trilogy about heaven, hell and purgatory on which he worked before his death. Wierzbicki strongly disagrees. "Krzysztof was tired of making films. He wanted to be closer to his friends and family, to real life, not life that was fiction. He would have continued to write scripts, teach and give advice to young film-makers, but in this decision he was absolutely serious."
Meanwhile, critical opinion about Kieslowski's films - which included quirky documentaries in the late Seventies, the epic moral and ethical inquiry of the Dekalog (10 hour-long films about the Ten Commandments) and his metaphysical explorations of fate, love and essential human values in Double Life and Red, White and Blue - remains divided.
While some rank him among the greats of European art cinema, others complain of pretension and lack of intellectual rigour.
"In Poland, everyone admires him now that he's dead, but Kieslowski had enemies when he was alive," says Wierzbicki bitterly. "You often heard critics say that his films were `full of tricks' or `less intellectual than they pretend to be' and complaining that his philosophy was very simple. But these people didn't understand Kieslowski's films. Really, the films were not sophisticated - but that was their strength. They are simple films dealing with basic truths. Searching for truth - the truth about life, about basic values - was Kieslowski's obsession."
What he most wanted to avoid was being didactic, says Wierzbicki. "He never wanted to give solutions to people. Absolutely not. In my film he says: `My profession is not to know but to ask questions', one question after another. He believed that every question asked takes us nearer to truth."
I'm So-So, which was shot on a friend's farm in the lakelands of north- eastern Poland, was made in the few months between Kieslowski's announcement of his retirement and his death at the age of 54 after a failed heart bypass operation.
"It was a horrible shock when he died," remembers Wierzbicki. Exhausted after making the Three Colours trilogy, Kieslowski had suffered a heart attack in August 1995. Yet by early 1996, freed from the stress of film-making, he seemed to have recovered.
"When he went for the operation, he treated it like a visit to the dentist. He was full of life and energy. He said: `I'll be out in three days.' He had even ordered a new car. He said to his wife: `Call the garage and tell them to prepare this car, because I've waited too long for it. When I'm back from the hospital I'll give them an argument like they never had before.'
"Now he is gone. It is the greatest tragedy and sadness for us. After Krzysztof died, someone said to me: `It is good that you made this film of him.' I told him: `I would prefer to have Kieslowski living.'
"Film is nothing, but life is something important. Kieslowski also told us this. He said films pass. Life is what matters."
Krzysztof Wierzbicki will be talking about `I'm So-So' after screenings of the film at the Polish Cultural Institute tonight and, as part of a short Kieslowski season, at the Curzon Soho, London, on Saturday.