One of the book's most provocative observations is that the core principles of both health and financial wellbeing were known, practised, and documented by ancient civilisations long before modern medicine or modern finance existed. Ancient Greek physicians prescribed walking and sleep as primary medicine. Ancient Chinese philosophy emphasised moderation and balance as the foundation of health. Stoic philosophy articulated a form of financial discipline — distinguish between what is necessary and what is merely desired — that matches the most sophisticated modern financial planning. The implication is uncomfortable: the reason populations in the modern world are less healthy and less financially secure than they could be is not a lack of information or technology. It is a failure of application and environment. We know what works. We live in environments designed to prevent us from doing it.