"In 1978 when the book Living Systems was published, it contained the prediction that the sciences that were concerned with biological and social sciences would, in the future, be stated as rigorously as the “hard sciences” that study such nonliving phenomenon as temperature, distance, and the interaction of chemical elements. Principles of Quantitative Living Systems Science, the first of a planned series of three books, begins an attempt to fulfill that prediction... It is our opinion that this book represents an important step in the development of a quantitative living systems science... As Simms shows, the concepts of available energy and the capacity to direct energy, as well as the causative relationship between information and behavior, are useful in the analysis of behavior... The systems with which this first book of the series is concerned are mainly at the level of the cell and the animal organ and organism.... It will be interesting to see how the science is applied in later volumes to the complex behaviors of human being, and higher level systems."