I was hesitant to write this book. It is because I think everything we say or write for the ears or the eyes of others, rather than our own, are only one facet of the Universe. It is because, in the happiest of the cases, we can reveal the trajectories of the system that we, ourselves, are.But never can we describe the dynamics of the systems represented by those that we interact with, which are sensitive to their own small perturbations.