Ramon Llull (ca. 1232-1316), mystic, missionary, philosopher, lay theologian, and one of the founding fathers of Catalan literature, was chiefly known in his own time and in subsequent generations as the inventor of a combinatorial, semi-mechanical method of demonstration, which he called his 'Art' and which he had developed to free interreligious debate from its fruitless textual base. Most of the extensive modern literature has been dedicated to mapping the foundations of Llull's system, with little attempt to see how he used and combined these foundations to produce actual demonstrations. This book, in a series of explications de textes, tries to explain what kind of demonstrative systems he developed during the two main stages of the 'Art', how they finally evolved into an adaptation of key aspects of medieval Aristotelian logic, and why the 'Art' was central to all Llull's endeavors.