My Friend Ricardo Ferreira, an Impressive Natural Philosopher

I have met, during my life, only two people to whom I would immediately and heartily reserve the title of natural philosopher – a title which in my personal conception designates the supreme form of science, the one that was practiced by Aristotle. They are Murray Gell-Mann, the Nobel laureate in Physics, and Ricardo Ferreira. These brief lines are dedicated to the celebration of the 80th birthday anniversary of the latter. I first met him, as far as I remember, around 1980, at the Centro Brasileiro de Pesquisas Físicas (CBPF). He was joining the Department of Theoretical Physics that I was heading. Immediately after, I resigned as Head: I was less than 40 years old, and I felt very embarrased to have as an administrative subordinate a scientist of the stature of Ricardo. We immediately did new elections, and he became the Head of the department. Sometime after, there was a minor conflict with somebody who (irresponsibly) accused him of having neglected on purpose some administrative demand. Such a suspicion was unacceptable by Ricardo, and he resigned on the spot. He referred, while resigning, to his father Antonio Ferreira, and behaved like he always did, with courage. Frequently, the manner through which a man deals with adversity gives the measure of his character. Konrad Lorenz, the Nobel laureate in Medicine, wrote in a couple of places that there are some events that, in some animal species, cause imprint. For me, in some sense, that was it. Ricardo’s scientific curriculum, the essential honesty and generosity of his personality, his reference to his father, and his courage, was good enough for me: from that point on, it became clear in my mind that I wanted to become his friend, as if he was a sort of (second) older brother for me. And, indeed, slowly, we started becoming friends – Saint-Exupery brilliantly describes such things in his amazing Le Petit Prince. Some years later, another institutional crisis occurred, involving myself this time. I was once again Head – of th