All the content of the Introduction and Lessons are an adaptation from the book "Fundamentos para una Teoría del derecho" written by Dr. Elio Gallego Garcia (Dykinson 2003), who has kindly allowed me to translate them into English for academic purposes. The selection of readings is my whole responsibility. With them I do not intend to present an exhaustive list of Classic texts, but to introduce our readers in the same trend that inspired many great jurists from different places, times and traditions. My only purpose is to invite them to get involved in an unforgettable dialogue with the Classics, trying to understand our current legal issues from their perspective. Oxford University, Faculty of Law. Institute of European and Comparative Law, July 2012.