 I'm a mathematical physicist and I came to the IHS in 1964. How did I choose to come here? Let me start at the beginning. My university studies took place in Belgium, which was then my home country. I started with two years of civil engineering, then proceeded to physics and mathematics and ended up with a PhD in physics from the Free University of Brussels in 1959. Actually, I had spent time at the ETH, the Federal Institute of Technology in Zurich, before and after my PhD, and that's where my scientific research career really started. In 1962, I moved for two years to the Institute for Advanced Study in Princeton, New Jersey in the United States, and then at the end of these two years, I could either stay in the US or go back to Zurich, but another possibility opened up, which was a new institute called IHS in Bursarivette. My wife was in favor of Bure because it was in France and I accepted a permanent position there. As I arrived here, I found that the place was fantastically good from a scientific point of view and very pleasantly located. However, the financial situation was bordering on the catastrophic, but it didn't bother me too much because science in those days was rather different from what it has become. In fact, there were few research scientists and there was a lot of money for science. So, I moved to the IHS, which was a great place, but I kept ready to jump to another country if the IHS should collapse. This attitude has served me well throughout my career. I want to talk about the golden period at the Institut des Hauts d'Études scientifiques. Have I known golden periods in other places? Well, I have been in the academic world for over 60 years in various countries and I have seen a number of normally good places and a few great ones. The difference is that in great places I have really felt pushed forward intellectually by interactions with other people. It may happen that a single scientist creates a great place around him in his field of competence. That was the case with Réciost in Guadalupe Field, Syrie, in Zurich in the 1960s and it still is the case now with George Liebowitz in Statistical Mechanics at Radgers University. However, a multidisciplinary great place may also arise when several scientists share the responsibility of scientific organization. A superb example was the Institute for Advanced Study in Princeton when I visited there from 1962 to 1964. At that time, T. D. Lee, C. N. Yang, Freeman Dyson, Robert Oppenheimer and others were around in physics. Another superb example was the IHS when I joined Alexander Grotendeck, René Tom and Louis Michel as a permanent member there in 1964. So-called permanent members were named given at the IHS to the faculty and there were also temporary visitors. Unfortunately, great places need not stay great forever. For instance, when I went back to the Institute for Advanced Study in Princeton in 1970-71, there was a dispute raging between physicists and mathematicians and the place for me was no longer great. At the IHS, there was also a period of crisis in 1970, which is when Grotendeck left. But about from that, the IHS has enjoyed several decades of greatness. This is what I think of as the golden period of the IHS and that's what I'm going to talk about. What makes a place great rather than just good? Well, first you have to start with good people. Since I'm one of those people I describe as good, this may sound a bit arrogant, but let me say that at the time that I'm discussing, the permanent members at the IHS were all known internationally for their work and had international connections that were very useful to get people invited. The permanent members of the IHS were certainly not mediocre at this time and let me say that as of now they are still not mediocre. The IHS permanent members still form a group that can be compared without disadvantage to the faculty at the Institute for Advanced Study in Princeton. Let me add that Leon Motschan, the first director and creator of the IHS was certainly also not a mediocre person. The IHS started with good people but there's no simple recipe to ensure that you will obtain a great place. At the beginning, the IHS had one great asset. Following the model of the Institute for Advanced Study in Princeton, the scientific decisions were taken by the faculty. This means that the permanent members used their international connections to seek out well-established good people and new talents to visit the IHS in Bursuivet. The quality of people who came is impressive. For instance, Jean-Pierre Serre and Irving Siegel stayed here for a year. My wife has a list of those people we had for dinner at home. This includes Freeman Dyson, Eugene Wigner, Rudolf Piles and many, many more. This was an impressive period. Well, an able administrator will ask specialists to rate application lambda versus application lambda prime but one can do better than that. Forget about lambda, lambda prime and seek out double capital A. The early IHS permanent members were not specialists. Grotendijk pointedly said that he was a generalist, not a specialist. So when the decisions of scientific policy were taken after discussion between the competent people who would implement these decisions, you obtained a coherent program where an able administrator could take decisions that follow the fashion, the decisions reached by the permanent members of the IHS were ahead of fashion. It's not easy at all to make the right choices of scientific policy. Going ahead of fashion means that you risk to be wrong but if you just follow fashion then you are certain to remain somewhat mediocre. There were heated discussions between the permanent members and the director in what was then the scientific committee of the IHS which took the scientific decisions and it is tempting to remove these heated scientific discussions to avoid trouble. But then one is likely to remove the greatness of the science one is trying to get going. Let me try to say briefly what I got out of the IHS golden period. When I came to the IHS I was working in equilibrium statistical mechanics which is an area of theoretical physics which has a remarkably rich underlying mathematical structure. In particular with De Bruyne and Lenford we obtained a local global understanding of the infinite volume equilibrium states of statistical mechanics and the name DLR equation was later introduced to describe our result. I wrote two books on the structure of equilibrium statistical mechanics. At the same time I did something completely different namely I listened to talks by René Tom on differentiable dynamical systems and I also interacted with Steve Smale and his collaborators who taught me the theory of hyperbolic dynamical systems. So two completely different subjects and then a miracle occurred the Russian Yasha Sinai found a deep relation between equilibrium statistical mechanics and hyperbolic dynamics based on what he called Markov partitions. This opened a whole new field in which I had the competence to work. I introduced the concept of transfer operators contributed to the study of Sinai, Orwell, Bowen measures and so on. These were important for the understanding of hydrodynamic turbulence and later led to the theory of chaos and this in a nutshell is what I did during the golden years of the IHES. Let me explain the place and role of the IHES in those days in relation to French science and also more internationally. The statutes of the IHES did not indicate any specific role in French science. This role emerged from personal relations of the permanent members with French colleagues and the relation was different actually for physicists and mathematicians. In mathematics there were series of talks the Seminaire Tom, the Seminaire Grotendijk and later the Seminaire de lignes which were well attended by people from Orsay, Paris and also international visitors like Steve Smale and Barry Mazer. Grotendijk and later de lignes had a number of students collaborators which were either French or coming from abroad. In physics the situation was a bit different. There was a common seminar which I started and was soon joined by Louis Michel and later other permanent members. This was more like a physics colloquium in a very wide sense. We asked talks from all kinds of international visitors to the Paris area, Benoît Mandelbrot being a typical example. The physics seminars were also well attended by people from Orsay, Sackler, etc. who came whenever the speaker or the title of the talk interested them. There was also an intense collaboration an interaction between the permanent members and the international visitors. The DLR equations that I mentioned earlier were a result from my collaboration with Oscar Landford who was then a visitor and the D is for the Brouchin who could not leave the Soviet Union but we corresponded with him and exchanged publications. I was a colleague of Grotendijk at the IHS for several years. What can I say about him? Grotendijk was one of several examples of people who made remarkable contributions extraordinary contributions to science and had otherwise a difficult life. I think of Galileo or Turing. The way in which Grotendijk abandoned mathematics also reminds me of the poet Arthur Rimbaud who abandoned a literary career for some obscure traffic in East Africa. One could also mention Newton and his various extra scientific preoccupations. The names just mentioned indicate Life Center not on pursuing a successful career but on trying to understand something general which was important to those people. At this moment let me interrupt the discussion of Grotendijk with a person's story. Early in my career I received a letter asking if I would accept a certain little scientific prize. I answered politely saying in my opinion thanks but no thanks I didn't care for scientific prizes. Then a little later after having forgotten about this prize I got another letter saying congratulations you won the X prize and I felt that I couldn't refuse it. Later I progressively understood that if you want to make a career in high level research you have to accept prize become member of academies and so on. That's not what I had in mind when I started doing science but that's how it turned out to be. Grotendijk would say that I got corrupted. Now more interesting for me than scientific prizes were hiking trips that I took mostly alone in remote parts of Mexico Iran, Ecuador and so on and these were important experiences for me but when I talked about those trips to Colise they often thought that I was boasting about physical prizes which was absolutely not the case. So I was afraid from talking about these hiking trips and also about reading Abela's Historia Calamitatum in Latin or other things that were important for me but that I understood I'd better not talk about. In this way I have survived better in the scientific world than Grotendijk or Galileo or Turing and this is not because I was scientific better but because perhaps I was a trifle more prudent. Let me return to Grotendijk. He was the son of a Russian anarchist who was traded during the Second World War by the French authorities to the German authorities and killed in Auschwitz. On top of being an anarchist he was also a Jew. Now Grotendijk himself was not an active anarchist but you can understand that he lacked the healthy respect for authorities which keeps you out of trouble. Politically he was incredibly naive. Having personally interacted with Grotendijk studied some small part of his mathematics and read part of his non-mathematical writings I think I have a unified view of who he was. He wrote, for my whole life my ambition as a mathematician or rather my joy and passion have constantly been to discover evident things. The person who wrote that was the same person who was incredibly naive politically. The person with the power of decision to create whole new branches of mathematics is also the same person who had little respect for authorities. The person who spent days and nights developing a new mathematical world is also the person who quit mathematics and spent his time doing what he called meditation which actually meant writing. Grotendijk did not leave mathematics and become insane. He pursued a life quest which was essential to him.