One source of (dis)unity in psychology is often ignored, namely differences among psychologists in the way they relate theories and data to the world. Personal differences between interpretation styles contribute to disunity and discontinuity within psychology. The same data as well as the same concepts and theories may be interpreted in different ways, thereby adding fuel to misunderstanding, apparent "incommensurability', etc. In this paper two opposite styles of interpretation are introduced. The works of Hermann von Helmholtz and Ernst Mach serve as examples. The paper concludes by noting the consequences of different interpretation styles in contemporary psychology.