Warsaw Zoo had a villa in it, a white house with a glass conservatory, standing among the enclosures on the east bank of the river.
The director lived there with his family. His name was Jan Zabinski. His wife was Antonina. Their son Ryszard was born in nineteen thirty two.
It was a strange and rather wonderful place to grow up. Antonina had a gift with animals that everybody who wrote about her mentions, and the house was permanently full of them. Orphaned lynx cubs slept in the bedrooms. A badger came in and out. There was a cockatoo, a hamster, and at one point a young rabbit that lived on a sofa.
By the end of the war, the things living in that house and in the empty cages outside it were mostly people.
In September nineteen thirty nine, Warsaw was bombed and then besieged, and the zoo, which sat near the river opposite the city centre, was hit repeatedly.
Enclosures were blown open. Animals were killed in their cages, and others got out and ran through a burning city, which produced scenes that survivors described for the rest of their lives: seals on the riverbank, a camel wandering a street, an escaped elephant.
Then came the second act, and it was worse in a colder way.
The director of Berlin Zoo, Lutz Heck, arrived. He had known Jan Zabinski professionally for years. He inspected the surviving animals, made a list, and shipped the valuable ones to German zoos.
Then, at Christmas, he organised a private shooting party for German officers, and they went round the remaining animals and shot them for sport, in their enclosures, in front of the keepers.
By the beginning of nineteen forty, Warsaw Zoo had no animals. It had a director, a caretaker's staff, a set of empty buildings, and a large amount of unused space in the middle of a capital city.
Jan persuaded the German administration to let him use the grounds for something useful, and for a while it became a pig farm, supplying meat, and later a fur farm.
The pigs needed feeding, and feeding pigs means collecting food waste. So Jan applied for, and received, a permit to enter the Warsaw Ghetto to collect scraps from its kitchens.
That permit is the hinge of this entire story.
The ghetto was a walled district of the city into which around four hundred thousand people had been forced. Getting in and out required documents. Jan now had documents, and a vehicle, and a routine reason to make the journey regularly, and a set of large containers.
He was also, by this point, a member of the Polish underground army, and he had an old professional connection to the ghetto because he had worked there as a city parks official before the walls went up. He knew people inside it.
So he started bringing people out. Under the scraps. In the containers. In a sack, in a crate, on the floor of the van under sacking.
The zoo turned out to be an almost perfect hiding place, for reasons nobody had designed.
It was large. It was walled. It had dozens of separate buildings, most of them empty, none of them overlooked. It had reasons for vehicles to come and go and for strangers in overalls to be about the grounds. And it was on the wrong side of the river from the centre of the city, which meant fewer patrols.
People were hidden in the empty animal houses: in the pheasant house, in the lion house, in what had been the elephant enclosure. Others lived in the villa itself, in cupboards, in the attic, and in a tunnel that ran from the house to one of the enclosures.
Most people did not stay long. The zoo was usually a stop of a few days or weeks while false papers were prepared and somewhere permanent was found. A few stayed for years.
The estimate that the Zabinskis themselves gave afterwards, and that is generally accepted, is that around three hundred people passed through.
Everyone hidden was given a code name taken from an animal, and the animals, in return, were given human names, so that a conversation in the kitchen about Squirrel or Starling meant nothing at all to a stranger listening at the door.
German soldiers came to the zoo constantly. It was a useful place with vehicles and storage, and officers dropped in to see the pigs or to hunt in the grounds or simply because they were bored.
So there had to be a warning system, and it had to be one that could operate instantly, from anywhere in the house, without a word being spoken.
Antonina used the piano.
She played a particular light tune from an operetta, one with a chorus about going away to Crete, and it meant one thing: go, hide, now. Anybody in the house or within earshot of the open windows knew to get into the cupboards or down the tunnel.
When the danger passed, she played something else, and people came out.
The whole arrangement rested on a woman being able to sit down at a piano and play a cheerful tune, correctly, at speed, while soldiers walked up the path. Ryszard, who was a small boy through all of it, remembered his mother's absolute calm as the thing that held the house together, and he also remembered being told that he must never, under any circumstances, mention any of the guests to anybody, which is a heavy instruction for a seven-year-old.
In August nineteen forty four, the Polish underground rose against the German occupation of Warsaw, and Jan Zabinski fought in it. He was shot in the neck, survived, and was taken prisoner and sent to a camp in Germany.
Antonina was left alone with two children, one of them a baby, and with people still hidden, in a city that was systematically destroyed street by street after the rising failed. She got them out and kept going.
Jan came back after the war. The zoo was rebuilt and he was its director again until the nineteen fifties.
In nineteen sixty five, Jan and Antonina Zabinski were both named Righteous Among the Nations.
Jan was asked, more than once, why he had done it, and he gave an answer that irritated interviewers because it was so flat. He said he did it because it was the right thing to do, and that he did not deserve special praise for behaving decently, and that he was more proud of his work with animals.
Antonina wrote children's books afterwards. Several of them were about animals, and one of them was about a young badger.
Most of what we know in detail comes from Antonina's own diaries, which she kept through the war, and which are the basis of a book called The Zookeeper's Wife, written by Diane Ackerman in two thousand and seven, and of a film made from it.
The zoo is still there and still open. It has animals again. There is a plaque, and the villa can be visited, and the tunnel is still under it.
It is worth being clear about the danger. In occupied Poland, unlike in Denmark, the penalty for hiding a Jewish person was death, and not only for the person who did it but routinely for their entire family. The Zabinskis had two children in that house. Every single day of five years, they were choosing that.
Here is something to think about tonight. Lutz Heck and Jan Zabinski were both zoo directors, both experts, both men who had spent their lives caring for animals, and they had known each other for years. One of them shot the animals for entertainment and the other filled the empty cages with people. What do you think made the difference between them?