Psychology as a self-aspiring, ambitious, developmental science faces the crucial limit of time—both theoretically and practically. The issue of time in constructing psychology’s theories is a major unresolved metatheoretical task. This raises several questions about generalization of knowledge: which is the time length of breath of psychological theories? Which is the temporal dimension of psychological processes? In this article we discuss the role of different axiomatic assumptions about time in the construction of psychological theories. How could different theories include a concept of time—or fail to do that? How can they generalize with respect to time? The different conceptions of time often remain implicit, while shaping the concepts used in understanding psychological processes. Any preconception about time in human development will foster the generalizability of theory, as well as a different ontological status of its concepts. For instance, the assumption that the human being changes—or remains the same—over the life span, will lead to theory building of different length, or shortness, of breath. We advance a metatheoretical perspective that axiomatically requires the inclusion of time in all research designs. Psychology as science that is time-free is a science of dead, rather than living and moving, human experience.