 Henry then argues in a number of different ways that knowledge is in fact possible. First, he draws from Augustine and Cicero. His weakest claim here is that we can rely upon the testimony of others; otherwise, he says, knowledge of the distant past, or of places that one has never visited, would be impossible. He also explains that one can trust the veracity of a given sense experience provided it hasn’t been contradicted by a more reliable sense experience. In addition, he says that even if one is dreaming, one still knows that one lives. As with many who follow him, Henry cites the certainty of the law of non-contradiction as well.