"An Iron Will" is a self-help book written by Orison Swett Marden, an American writer and founder of Success Magazine. The book was first published in 1901 and focuses on the importance of cultivating a strong and determined willpower to overcome obstacles and achieve success in life.

The central theme of the book revolves around the idea that a resolute and unyielding will is a key factor in achieving one's goals and overcoming challenges. Marden explores the concept of mental resilience and advocates for developing a mindset that can withstand setbacks and adversity.

He draws on real-life examples of individuals who have demonstrated exceptional willpower to illustrate his points. Marden emphasizes the power of positive thinking, perseverance, and self-discipline. He encourages readers to cultivate a positive mental attitude, set clear goals, and stay focused on their objectives despite obstacles and hardships.

The book also delves into the idea that challenges and difficulties can be opportunities for personal growth and development. Overall, "An Iron Will" is a classic work in the genre of self-help literature, offering timeless advice on building mental strength and determination to achieve success in various aspects of life.