What is the best self development book you have read and why ?

Think and Grow Rich 

is one of several old-school classics on this list and its place is well-earned. For twenty years, author Napoleon Hill studied the most successful people of his time, including Henry Ford and Alexander Graham Bell and chronicled those findings together into one neat little package.The main takeaway? A focused, burning desire (or the power of a made-up mind, what Wayne Dyer called intention), gives us the power to achieve or acquire what we want most in life.If you’re looking for insights on how to achieve your dream or a specific goal, this is a classic you can’t do without.The Power of Positive Thinking by Dr. Norman Vincent PealeDr. Peale’s classic is the quintessential self-help book, being one of just a handful of early books from around the 1950s that shaped the entire self-improvement space as a whole. For that reason, there are many themes in the book that you’ll see echoed throughout many of the other books on this list. However, the perspective is slightly different and a refreshing change.The value of positive thinking is such a basic mantra of self-improvement that it’s now almost overlooked. The Power of Positive Thinking is great for anyone looking to get back basics and learn some of the fundamental lessons that are critical to believing self-confidence and an optimistic mindset.The Magic of Thinking Big by David J. SchwartzThe Magic of Thinking Big is a book that I’ll always remember because reading it was probably the first time I was introduced to the true power of the mind. Like Peale’s Positive Thinking, this is another classic, so the examples and speech that Schwartz uses are often entertaining in themselves.Above all else, The Magic of Thinking Big will teach you not to short-change yourself. Think big, don’t settle, and watch as a simple shift in the way you think literally changes your results.The Magic of Thinking Big is great for anyone looking to learn more about how to use the mind to achieve higher levels of success.

I can’t remember if the author is Alan Watts or James Alan but I read over 300 pages of their writing and he is the most intelligent human teacher I’ve ever encountered. But I have a disclaimer, I suspect that after his death his family personally crafted new ideas and than sold them under his name and pretended they were written by him, because the style and content quality diverges greatly between the works he published and the works his child published under his name with the claim it was written by him but never published and was published by her after his death. 

the 7 habits of highly effective people..........

Why first:

Relationship: "For Couples Only," by Shaunti Feldhahn;

Work:  "Shop Class as Soulcraft;"

Spirituality:  "The Path of the Higher Self;" "The Following of Christ;" (2 titles).

The Bible.  It is full of ancient wisdom about navigating life. It outlines a way to greater peace and prosperity.  It outlines our purpose in life, God's plan for salvation, and the road to eternal happiness.  It establishes a moral compass from which to grow true character.  Millions believe it is God's communication with mankind.  IF there is a remote possibility that this is true, should you not make an effort to read it?  Don't discount the Bible as mythology or fables, it is much more than that.

Another non-Biblical books are "How to Win Friends and Influence People" by Dale Carnegie, and "The Seven Habits of Highly Successful People"

The Bible

Because it teaches you to live for something beyond yourself

The Tao Te Ching.  It's impossible to describe why, but that's OK.  That's life.