This book has been sixteen years aborning. In 1959-1960 the author sat in the lectures of S. Kakutani at Yale University and learned his first
lessons in ergodic theory. Notes taken in those lectures have evolved and
expanded over the years through the author's own lectures at Oregon
State University, have been garnished by his contact with distinguished
mentors and colleagues, and after numerous rewritings have assumed the
form of the present text.