When the Nazis overran France in the Spring of 1940, thousands of Jews attempted to cross the boarder south to Spain and Portugal. There was a major problem though: they needed visas, and the Portuguese government forbade its consuls in France at the time to issue any visas without prior approval from the Foreign Ministry.
Sousa Mendes, the Portuguese consul-general in the French city of Bordeaux during this period, defied the orders of the Estado Novo regime, issuing thousands of visas to Jewish refugees, saving their lives.
In his latest book, Homo Deus: A Brief History of Tomorrow, the Israeli historian, Yuval Noah Harari, cites this episode as an example of how written documents can change the course of a life.
History, Harari writes, is predominately based around a web of fictional stories. While the primal abilities of individual humans has really not changed, narratives that humans created to give meaning to their lives has grown exponentially: most notably since writing emerged 5,000 years ago in ancient Mesopotamia.
"Writing habituated people to think in terms of the written word, and not in terms of what they had experienced in the world," Harari explains, when we meet at his publishers office in central London.
"The written word therefore came to define reality. In a bureaucratic system, for instance, everybody knows that what is written on your form is far more important than reality."
The first written Sumerian records were on mundane subjects, such as taxation and ownership of land. Within a couple of centuries, however, priests and rabbis began writing religious scriptures that defined entire societies.
These stories - so Harari's argument goes - serve as the basic foundations for social cohesion in human societies.
Religion is a subject Harari spends considerable time dissecting over the course of his new book.
He grew up in a secular family in Israel. Nevertheless, the historian still regards himself as a person with a strong spiritual dimension.
"Spirituality is when you raise these big questions, such as who am I? What is the meaning of life? And what is my place in the world?"
Religion, on the other hand, Harari posits, is anything that confers superhuman legitimacy on human social structures. It also asserts that humans are subject to a system of moral laws that we cannot change.
"Religion is very important to human society," says Harari. "But the stories that stand at the bases of great world religions are just fictions. Mythologies, of course, are always essential. But they do not need to focus on God any more."
This was the focus of Harari's earlier book, Sapiens: A Brief History of Humankind, published in Israel four years ago, which became a best-seller when it was translated into English. It argued that liberal humanism is just another form of religion: where humanists worship humanity.
Harari concluded that book by looking into the future, claiming that homo sapiens is on the cusp of unprecedented change, because technological tools have given us the ability to dramatically reshape our species.
Homo Deus picks up where Sapiens left off. But Harari spends considerably more ink this time discussing the future.
"[Humans] are in the process of trying to acquire abilities that traditionally were thought to be divine," he says. "So we are becoming better than gods, because we can create living organisms according to our wishes."
Harari talks in very precise, methodical sentences. He also likes to skip between historical epochs - from billions of years ago straight back into the immediate future - every few minutes: mixing up science, mythology and religion in equal measure.
"According to the Bible," says Harari, "in the book of Genesis, God creates animals, plants, and humans, according to his wishes."
"But now we are learning how to engineer and manufacture living entities according to our wishes."
" In the 21st century, the main products of the economy will no longer be just food, textiles and vehicles. They will be bodies, brains, and minds."
Homo sapiens can now do something even the old gods couldn't do," says Harari, "create non-organic life".
"For four billion years - whether you believe in evolution, or you believe in divine creation - all of life was confined to the organic realm.
"So, whether you are an amoeba, a dinosaur, or a giraffe - until now you have been made of organic compounds.
"But now we are learning how to create non-organic life, like artificial intelligence. This is the biggest revolution in the history of life."
This revolution that is now on the horizon, he argues, will enable us as a species to re-engineer human minds.
This will see homo sapiens disappear. Then human history will come to an end and a completely new process of life will begin. The change will be so drastic, he says, that it's hard to even fathom what it will look like.
Still, always the ambitious thinker, he gives it his best shot.
"The attempt to re-engineer homo sapiens could happen in three different ways," Harari explains.
Firstly, by changing our biological infrastructure, or, by changing our DNA in our hormonal system. The second option is to create cyborgs. This would combine organic parts of our brain with inorganic parts: connecting our brain to various bionic devices. The third option - and the most extreme method - he believes, would be to completely abandon the organic core. This means creating non-organic life forms.
Essentially, this would be about creating artificial intelligence, or uploading human consciousness into computers and creating silicon-based life forms instead of carbon-based life forms.
Is this last option actually possible?
"I don't know," Harari admits. "But there are many people who think it is feasible, and there's billions of dollars being invested into the research."
If Silicon Valley gurus, such as Peter Thiel and Ray Kurzweil, believe that overcoming old age and death are real possibilities in this century, other tech geeks are also predicting another vital discovery: what makes us happy?
"Finding the key to happiness is going to be very difficult," says Harari without a hint of irony, "because you really need to decipher the inner workings of humanity [itself]".
Many people throughout history, Harari points out, believed the key to happiness for humans, was somewhere outside in the physical world, or in the workings of the social, and economic system.
Yet, despite all our progress, happiness levels have really not increased at all.
"There is no indication that people today are significantly more satisfied with life than they were 20,000 years ago," he says.
"This implies that the key to happiness is not about changing the world outside us. In other words, happiness begins within." However, when scientists talk about happiness within, Harari says it's important to note that they mean within the biochemical system of our body.
So this will require science to decipher the inner workings of the human organism.
The idea of humans trying to attain immortality, bliss, and divinity, isn't an original idea.
Actually, according to Harari, it really just reflects the traditional ideals of liberal humanism.
So,what will happen once the human experience - with the aid of post humanist technologies - becomes just another designable product, no different from any other item in the supermarket?
"Well that's one of the big questions of the century," says Harari, slightly unaware that his tone can sometimes descend into the histrionic and ridiculous simultaneously.
He adds: "It will certainly corrode the authority we give to human feelings.
"Presently, we think about human feelings as the highest authority in the world.
"In the fields of ethics, economics and politics, we don't expect our moral values to come from the gods or from scriptures, but from feelings."
As liberalism began to dominate western culture, politics, economics and society, over the course of the 20th century, Harari maintains that the entire discourse of human life began to be explained in terms of our feelings.
"That was all very well when feelings were beyond our understanding or control," says Harari.
" We could imagine feelings as some transcendent spark of life within ourselves: a kind of free will of the individual that gives guidance to the world."
Once scientists started deciphering human feelings though - and when they are able to manufacture human feelings on demand- Harari predicts unprecedented changes on the way for humanity.
"When we reach the point that you can actually engineer and manipulate human feelings, then our entire political, economic and moral system will have to undergo a tremendous revolution," he predicts.
"We will leave behind the humanist age: when human feelings were the highest authority. And something completely different will replace it."
Harari doesn't claim to know the answer to what that something will be. No doubt it will be the subject of his next epic tome.
