This is a book on what is perhaps the most burning and urgent of social issues of our times, namely, the relationship between the science of Economics and Ethics. It demonstrates that the modern view has reversed the true relationship and that it is a mistake of enormous practical significance, not unrelated to the vicissitudes that the modern economy has experienced in the past and, now worldwide, is undergoing at the present time. To regain the proper perspective on the relationship, we need to recover the practical wisdom of two of the geniuses of Ethics in the history of that study: Aristotle and St. Thomas Aquinas.