In the book, Bennett explores various topics related to mental efficiency, such as concentration, memory, willpower, and self-discipline, and provides practical advice on how to develop and strengthen these skills. He argues that mental efficiency is essential for success in any field, and that it can be cultivated through conscious effort and practice.One of the main messages of the book is that mental efficiency is not a natural talent, but a skill that can be learned and developed over time. Bennett encourages readers to take a proactive approach to their mental development, and to practice habits such as regular exercise, proper nutrition, and adequate rest in order to optimize their mental functioning.Overall, "Mental Efficiency" is a classic self-help book that provides practical advice and inspiration for anyone seeking to improve their mental abilities and achieve greater success in life. Its teachings continue to be relevant and valuable today, more than a century after its initial publication.