Dominic's education at Palencia gave him the knowledge he needed to overcome the Manicheans. With charity, the other concept that most defines the work and spirituality of the order, study became the method most used by the Dominicans in working to defend the Church against the perils that hounded it, and also of enlarging its authority over larger areas of the known world. In Dominic's thinking, it was impossible for men to preach what they did not or could not understand. When the brethren left Prouille, then, to begin their apostolic work, Dominic sent Matthew of Paris to establish a school near the University of Paris. This was the first of many Dominican schools established by the brethren, some near large universities throughout Europe.