separation of concerns

It is what I sometimes have called "the separation of concerns", which, even if not perfectly possible, is yet the only available technique for effective ordering of one's thoughts, that I know of. This is what I mean by "focusing one's attention upon some aspect": it does not mean ignoring the other aspects, it is just doing justice to the fact that from this aspect's point of view, the other is irrelevant. It is being one- and multiple-track minded simultaneously.

1974, Edsger W. Dijkstra, “On the role of scientific thought”, in Selected writings on Computing: A Personal Perspective

What we discover regarding legal transactions guided by rules of law and backed by fear of violence under the jurisdiction of political government, will hold true, in substance, of business transactions guided by the common rules of business and backed by fear of poverty under the jurisdiction of business concerns, and of moral transactions guided by accepted codes of conduct and backed by fear of opinion under the jurisdiction of cultural concerns. As already stated, this separation of concerns is a matter of predominance and not isolation, for the fear of violence, poverty and opinion are interwoven.

1924, John R. Commons, Legal Foundations of Capitalism