In our society in which communication is so wide-ranging and rapid we are witnessing a significant increase in the pace at which knowledge is produced and disseminated. Bodies of knowledge intersect as they cross borders between disciplines in the human and social sciences, and in the natural sciences, life sciences, and technological sciences. How do concepts, theories, and methods circulate, and how are they exchanged, borrowed, transferred, and transformed, when they cross from one discipline to another? In what ways does this interdisciplinary practice constitute a creative gain in the production of new knowledge, enabling us to understand problems that are impossible to solve from the perspective of a single discipline? The present article addresses these issues by defending the idea that, like other "modi operandi," interdisciplinarity is promoted by the circulation of concepts, theories, and methods, and by analogy or transfer across and beyond disciplinary borders that appear closed. The article is also an appeal for arbitrary borders between communities of subject specialists to be transcended, for creative but rigorous thinking in all subject areas, and for researchers to adopt an interdisciplinary outlook.