In this invective, in epistolary form, translated from Latin by María José Martín Velasco, Francesco Petrarca expresses his rejection of the concept of knowledge as an accumulation of information lacking existential relevance, and defends the value of knowledge to direct one’s steps towards the authentic source of light and truth, which for him is none other than Christ. In effect, we find ourselves before an authentic manifesto of Renaissance Christian humanism (not medieval, as those who identify humanism with atheism would like to believe) and as an inflamed and lively testimony of a man who, at the end of his life, postulates his own ignorance as the humble acceptance of the limitations of human reason, in the face of the arrogance of those who believe themselves wise for strictly following the lessons of Aristotle.