Dr. Norman Vincent Peale (May 31, 1898 – December 24, 1993) was a Protestant preacher and author (most notably of The Power of Positive Thinking) and a progenitor of the theory of "positive thinking".

Biography
"Positive thinking," as described by Peale could be broken down into a three step process of practicing repeated self-hypnosis, attaining "divine" or God's power to use for oneself, and eliminating and avoiding all negativity in life.
The first step in positive thinking is focused on the use of repeated "techniques." Peale describes positive thinking as first and foremost as "simply a series of practical and workable techniques for living a successful life."

Teachings
Peale's works came under criticism from theologians, mental health experts, scholars, and politicians. Critics appeared in the early 1950s after the publication of The Power of Positive Thinking, warning that Peale's message was dangerous and that he was a con man and fraud.
One major criticism of The Power of Positive Thinking is that the book is full of anecdotes that are hard to substantiate. Almost all of the experts and many of the testimonials that Peale quotes as supporting his philosophy are unnamed, unknown, or not sourced. Examples include a "famous psychologist,"
Adlai Stevenson was famously quoted as saying "I find Paul appealing and Peale appalling." (brainyquote.com)

People who have praised Dr. Peale

Change your thoughts and you change your world.
You can have peace of mind, improved health and an ever-increasing flow of energy. Life can be full of joy and satisfaction.
Those who are fired with an enthusiastic idea and who allow it to take hold and dominate their thoughts find that new worlds open for them. As long as enthusiasm holds out, so will new opportunities.
Any fact facing us is not as important as our attitude toward it, for that determines our success or failure. The way you think about a fact may defeat you before you ever do anything about it. You are overcome by the fact because you think you are.
Getting people to like you is merely the other side of liking them.
When you wholeheartedly adopt a 'with all your heart' attitude and go all out with the positive principle, you can do incredible things.
Believe in yourself. Have faith in your abilities! Without a humble but reasonable confidence in your own powers, you cannot be successful or happy.
The challenges in life are there not to break you, but to create you.
Empty pockets never held anyone back. Only empty heads and empty hearts can do that. Trivia

The Power of Positive Thinking, Ballantine Books; Reissue edition (August 1, 1996). ISBN 0-449-91147-0
Guide to Confident Living, Ballantine Books; Reissue edition (September 1, 1996). ISBN 0-449-91192-6
Six Attitudes for Winners, Tyndale House Publishers; (May 1, 1990). ISBN 0-8423-5906-0
Positive Thinking Every Day : An Inspiration for Each Day of the Year, Fireside; (December 6, 1993). ISBN 0-671-86891-8
Positive Imaging, Ballantine Books; Reissue edition (September 1, 1996). ISBN 0-449-91164-0
You Can If You Think You Can, Fireside Books; (August 26, 1987). ISBN 0-671-76591-4
Thought Conditioners, Foundation for Christian; Reprint edition (December 1, 1989). ISBN 99910-38-92-2
In God We Trust: A Positive Faith for Troubled Times, Thomas Nelson Inc; Reprint edition (November 1, 1995). ISBN 0-7852-7675-0
Norman Vincent Peale's Treasury of Courage and Confidence, Doubleday; (June 1970). ISBN 0-385-07062-4
My Favorite Hymns and the Stories Behind Them, Harpercollins; 1st ed edition (September 1, 1994). ISBN 0-06-066463-0
The Power of Positive Thinking for Young People, Random House Children's Books (A Division of Random House Group); (December 31, 1955). ISBN 0-437-95110-3
The Amazing Results of Positive Thinking, Fireside; Fireside edition (March 12, 2003). ISBN 0-7432-3483-9
Stay Alive All Your Life, Fawcett Books; Reissue edition (August 1, 1996). ISBN 0-449-91204-3