We are gathered here today to commemorate Carlos Chagas Filho, a great scientist, a great humanist and a towering moral figure. In honor of his memory this Symposium was organized, covering – on the one hand – various scientific disciplines, and – on the other hand – moral and philosophical problems either caused by science or which can be helped by science. Thus, the expression ‘challenges of sciences’ includes not only what we as scientists usually consider the latest results of the progress of science, but also the challenges provoked by science, in short – as is so well said in French ‘les défis de la science’. To me personally Carlos Chagas Filho was a great friend whom I had the privilege and pleasure of meeting in Israel in October 1963, and as a result of this visit he invited me to give a course in 1964 at his institute of biophysics in Rio de Janeiro. After that we met often, in Rio, Paris, Boston and – first and foremost – here in the Pontifical Academy of Sciences. We attended together many of the splendid study weeks, and I remember especially the study week we organized jointly on the role of non-specific immunity in the cure and prevention of cancer.
Carlos Chagas was enormously interested in all areas of science, but especially in those aspects which were of crucial importance to the progress of humanity. At the same time he was totally committed to the development of science in Brazil, and I am sure he would be exceedingly proud of the Brazilian achievement of sequencing the complete genome of the bacterium Xylella fastidiosa. The great achievement of Carlos Chagas Filho during his sixteen years at the helm of our Academy will never be forgotten. I would like to express my gratitude to the speakers at this memorial Symposium who have so enthusiastically accepted our invitation. I wish all a most successful and intellectually stimulating symposium.