Think and Grow Rich by Napoleon Hill is a foundational self-help book, revealing the "secret" to success through analyzing over 500 self-made millionaires like Andrew Carnegie, outlining 13 principles (Desire, Faith, Autosuggestion, etc.) to develop a success mindset, and emphasizing the power of a positive mental attitude, clear goals, and persistent action to achieve wealth and personal achievement, making it a classic in motivational literature.