The book "Testament of New Thought" was written by Ella Wheeler. This work is a classic work of the New Thought direction, which emphasizes positive thinking and the power of one's own consciousness. In the book, the author shares her own thoughts on how to tune your mind to success, joy and harmony in all areas of life. Through her words of wisdom and witty advice, Ella Wheeler inspires readers to reach their full potential and create a happy and successful life. "Testament of New Thought" is a book that helps to change the worldview and find inner peace.