The Preacher and the Preaching According to Gregory the Great, an Interpretation on 'Homilia in Evangelia' 1, 17 is an argument that has never been studied by someone as a thesis for licentiate or doctorate. This study, then, aims to present the thought of Gregory on the preacher and preaching, which he exposed in his Homilia in Evangelia 1, 17. For him, preaching should not be problematic, although it is not easy; preaching always implies a journey of the interior life, with Gregory calls an experience of God. Preaching should be an aid in the process of transformation.