[{Image src='de-moura-carlos-4.jpg' caption='' width='550' alt='Carlos A. de Moura' class='image_left'}]''__Mathematical Modeling- an art, a duty, a danger__''\\ \\ Carlos A. de Moura, Rio de Janeiro State University, Brazil\\ \\ __Abstract:__ \\ \\ Mathematical modelling is an essential component of many scientific studies and, we could even say, a sensible part of our everyday experience. Sciences based on mathematical models deserve to be called “exact". This allows them to bear a more respect-full status as compared to the ones known as “soft". An important fact is overlooked, though: to model is to pretend. When facing a mathematical truth no questioning may be posed and often one is led 8 to the same attitude towards a mathematical model. But mathematical conclusions about a model are true for that model, not necessarily for the modelled phenomenon. \\ \\ These remarks are intended to guide the discussion on a topic that nowadays is of utmost importance: the use of numerical parameters to rate scientific papers and journals.