Hundreds of free ebooks are available online, but what is the best free e-book on prosperity? Of course, "the best" is always a relative term, and in the end it comes down to which book resonates most with you. Having said that, we'll briefly review three of the most popular prosperity ebooks available free online.

Note: All of the following titles are in the PUBLIC DOMAIN and are available free from a number of different websites.

1. The Science of Getting Rich by Wallace Wattles. Written in 1906, Wattle's book is influenced heavily by the ancient Indian philosophy of monism, as well as writers such as Spinoza and Emerson. It is primarily a practical book which outlines the importance of gratitude, visualization and the "creative mindset."

This book also influenced many modern prosperity works, such as Think and Grow Rich and The Millionaire Mind. And although Wattles never used the phrase "the Law of Attraction," his book is said to have influenced the highly-successful film, The Secret.

Verdict: An excellent introduction to the prosperity-mindset and positive thinking. Overall rating: 5 out of 5 stars.

2. The Master Key System by Charles F. Haanel. This classic e-book on prosperity has many fans, and is well worth a look. Written in 1912, The Master Key System was originally designed as a mail-order success course in 24 parts, which outline the scientific principles that govern achievement and prosperity.

Haanel's work is informative and concise, though it lacks the motivational aspects present in The Science of Getting Rich. The Master Key System is said to have influenced much of the so-called "New Thought" religious philosophy of the early 1900s. The book was even banned by the Catholic Church in 1933, and only began to reappear over the last 25 years.

Verdict: The Master Key System is a good introduction to the natural principles of success and prosperity, but lacks motivational impact at times. Overall rating: 4 out of 5 stars.

3. As a Man Thinketh by James Allen. James Allen was born in Leicester England and wrote more than 20 books before dying at the young age of 48. His most important work, As a Man Thinketh, is a study of human potential and mind power.

Allen drew from a variety of influences as diverse as Protestant Liberalism and Zen Buddhism to support his thesis that our circumstances in life are a direct indication of our character. In other words, we create our life by design -- not by chance or fate.

This book challenges the reader to accept responsibility for the results they see in their life, and then move forward with an understanding that our inner state will always be perfectly reflected in our outer circumstances.

Unlike other personal development books of its era, As a Man Thinketh also discusses the power of meditation and so-called "altered states." In this regard, it was certainly ahead of it's time. Modern books such as Norman Vincent Peale's The Power of Positive Thinking are obviously influenced by the conclusions of As a Man Thinketh.

Verdict: As a Man Thinketh is not a beginner's guide to prosperity, but it deserves it's standing as a personal development classic. Overall rating: 5 out of 5 stars.

All of these books were written nearly a century ago or more, and have stood the test of time. Choosing the best free e-book on prosperity from these three will largely be a matter of your personal taste; however, you're unlikely to go wrong with any of these titles. They all represent an advanced understanding of the science of prosperity and abundant living.