XYZ System is a CASE environment based on temporal logic and conforming to various ways of programming such as programming with HLL, hierarchical specification or production rules, sequential or concurrent, textual or graphical, etc. All these programming paradigms can be unified with a uniform framework of a temporal logic language. The system is designed with the idea to keep good balance between the theoretical rationalism and the engineering pragmatism. In this paper, this idea is illustrated from philosophical point of view.