Machine learning risks becoming a mystical religion. I am not only referring to people actually worshipping “AI gods”, but the general tendency to think that AI will guide our society to enlightenment, solving most of the problems, without us being able to understand it in its superiority. Approaching one of the biggest “technological disruptions” of the second decade of the 2000s with an act of faith is not the safest thing to do. We need to understand both the structure and the consequences of the algorithms we use. Which location could be better to discuss about these challenges than a former monastery in the Tuscan countryside? Between September 10 and 13 2019 this wonderful place (Certosa di Pontignano) was the frame of the conference LOD2019, the Fifth International Conference on Machine Learning, Optimization, and Data Science.