Abstract
Taking into account the critical analysis of the first scientific magazines written in Spanish during the so-called “República de las letras”, the author explores the progressive constitution of the written press as an ideal public space to express Opinion and Thought. The study looks over the formation of the abovementioned public space from a point of view of its dimension and both as a cognitive and juridic agent. In this article, the contradictions, paradoxes and limitations of that double dimension are explored. The two dimensions, namely the cognitive and juridical, are examined in the context of the public opinion for both the civil society and the scientific one.