Organization constitutes an overarching hypoth- esis that frames the intelligibility of biological objects. We offer a specific characterization of organization in terms of closure of con- straints. The adoption of organization as a principle fosters an orig- inal approach to biological stability. We elaborate on its articulation with the two other theoretical principles addressed in this session and use them to discuss what it means to access empirical objects in biology. Finally, we address measurement and precision in biology.