"The best thing to do id to get healed of negatives in life, become filled with faith" hence goes the words by Dr Peale as it appears n the introduction of the book and that exactly is the purpose and vision of the book. He seeks to replace the negativities in life with a positive outlook through the medium of prayer and faith. Dr Peale was a minister by occupation and this has aided him in bearing witness to the many sufferings there is and as he himself states that the sheer volume if published as a book could be consider as the account of all human suffering. This very aspect of his occupation has also helped him witness many miracles and has shown him what the human spirit can achieve ones it is determined to so so. This book is a guide to help realize that potential.
That being said one of the greatest back-draws that I experienced when reading the book was also culminating from the fact Dr Peale was a minister and that his proximity to his religion and its intricacies. The book is full of references to Bible, anecdotes, events and stories from the Bible and the christian religious world view. Now I don't mean to say that the book is a christian doctrine, but any person totally unaware or illiterate of the christian world view would find it hard to comprehend and fully appreciate the wisdom of Dr Peale.
The whole essence of the book can be found in the phrase "Be filled with love and faith" and he prophesies that all your vows will be gone once that is achieved. The book is an excellent guide to any one who finds himself in a doldrum and seeks to escape that impasse. Once you are willing to look deep into the elements of christianity in this book and seek out its meaning and why he choses to use it, this becomes and excellent guide but even without that all you have to do look beyond them and the book will serve its purpose, and will help navigate you through your life.