In classical logic, it is evident that there is a clear relationship between the conditional and the universally quantified sentences. In this paper, I claim that this relationship is not only a requirement of that logic, but we also have important evidence that seems to prove that the human mind assumes it in a natural way by virtue of purely psychological reasons. To show this, I resort to an ancient text authored by Sextus Empiricus, in which the relationship is explained in a very precise manner, and the framework given by a current cognitive theory, the mental models theory, in which descriptions of the way it appears that human beings tend to understand both conditionals and the universally quantified sentences are included.