This book, a semantic study of the word ars, begins at the commencement of latin literature and includes the ciceronian era, the perspective being both lexicographic and historical. After the etymological research, which highlights the fundamental elements of order and of ability for organization, the various meanings of ars are classified applying the methods of componential analysis. The evolution of this semantic structure is seen on two levels : the archaic period and the first century (dominated globally by Cicero). During this second era new meanings of ars began to appear ("a special science", "a technique or method", "a theory, system" and "a treatise"), essentially borrowed from the greek word "technè" from which "ars" is the latin counterpart, notably apparent in rhetorical and philosophical works. These new definitions do not replace the older ones ("skill" and "behaviour, practices", "professional skill, craftsmanship" and "a profession, craft") : the plural "artes bonae", which can be synonymous with "artes liberales" (the basis of a free man culture) was used concurrently to designate the traditional roman virtues as opposed to the greek "uirtutes". Out of this study one surmises that "ars" like "technè" is not limited to practical knowledge but provides for a larger explanation of human knowledge.