Here is the long-delayed publication of the first summary of the principles of ethology, by the man most responsible for the growth of that science. Lorenz (Here Am I--Where Are You?, 1991, etc.) was confined in a Russian POW camp from 1944 to 1948, when he composed what he saw as the first volume of a textbook on comparative behavioral research. While the book remained unpublished, Lorenz reworked many of its ideas for publications on which his stature as the founder of ethology rests. The manuscript was lost in the early '60s, to be recovered only after the author's death in 1989. Now, 50 years after it was begun, it is in print, edited by von Cranach, Lorenz's daughter, and translated from the German by Martin (who worked with Lorenz on the English versions of several of his earlier books). In retrospect, it is easy to see that the ``Russian manuscript'' was a seminal work; only the most basic research had been done in the field that would eventually be called ethology. But its belated publication robs it of much of its impact; much of the material is now either familiar or dated. Lorenz spends half the book laying down fundamental principles: on the relationship of scientific and philosophical research, on scientific methodology, on the specific methods and assumptions of the biological sciences. Moreover, his arguments must be seen in the context of the intellectual climate of the 1940s; for example, his comments on evolution take the view that selection promotes the survival of the species, whereas today it is seen as primarily benefiting individuals. Lorenz is a vigorous writer-- his style is full of exclamations and literary quotations. As a result, this work is consistently readable, even for the nonspecialist. A pioneering work in its field, now interesting primarily as a historical document and the first great work of an unusually literate scientist.