After a brief review of dynamical systems theory, which is a key to understanding the dynamic process of biological states, we present the methodology adopted in this volume. It consists of (A) macroscopic phenomenological theory based on biological robustness, (B) universal statistical laws at the microscopic level, (C) general laws derived as a consequence of macro-micro consistency, (D) hierarchies with different time scales, and (E) experimental approaches to uncover universal properties and laws, as well as (F) consequences of a possible breakdown of consistency. To illustrate the consistency between cellular growth and molecular replication, we present examples of general statistical laws in gene expressions and the correlated change of expression levels across genes in response to environmental changes, together with their experimental confirmation. Later chapters explain the application of the methodology (A–F) to reveal fundamental properties in life.