Though first published back in 1915, this comparatively short work has inspired philosophers and thinkers since its first appearance, and has been cited by many as their insight and inspiration. Frederick Bailes, to take just one example, said that the application of Troward's insights enabled him to overcome a supposedly "incurable" disease (diabetes).
What is so important about the Troward insight? Essentially, Troward was a judge who applied rigorous logic and the evaluation of evidence to understand the way the universe came into existence, and how it works. He demonstrates that, as neither matter nor energy could (in themselves) have initiated the design process, there must be a creative inspiration - this may be called God, though Toward prefers "Spirit". A later readership might call it "the cosmos". The name doesn't matter - the principle is that of a guiding and designing intelligence, essential to the creation of a logical universe.
From this, Troward argues, it follows that the process of creation must be one of thought - the universe was created by the application of rational design to the static elements of matter and energy. From this, it follows that we should employ the same design process to achieve our objectives, whatever these may be.
I'm sure that I've not explained this very well, but hope that this will get you thinking. Read this book. Not only can it change lives - better yet, it can show you how, and why, the change process operates.