Horatio Dresser discusses the things which matter in life - our beliefs, our conduct and deeds, our sense of self and the nature of the physical world around us.
As a leading figure in the New Thought religious system, Dresser was experienced with describing the various aspects of life that carry importance in the spiritual context. He broadens the usual discussions of belief in God and faith in Jesus to philosophical topics such the human appreciation for beauty and the notion of fate. How people can use silence to attune and contemplate their beliefs, and how a person's health benefits from such thoughts, is discussed.
The author also explains how humans can alter their will in order to secure a better and more contented life, and achieve their desires in a manner which is spiritually and mentally beneficial. This process is gradual, and involves changing habits in how we think and act - the rewards however are substantial. Various routes to such a happy end are detailed; practices such as asceticism and concluding fear being listed as methods.
Overall, The Heart of It is a fine introduction and primer on the New Thought spiritual movement, giving readers a taste of its philosophic and spiritual aspects.