"Lessons in Truth: A Course of Twelve Lessons in Practical Christianity" is the core text on Unity Church teachings and it is one of the best representatives of New Thought philosophy. The spiritual models presented in Dr. Cady's lessons show us how to enhance our confidence and inner power, and improve our spiritual development. In the beginning of 1892, a series of articles titled Lessons in Truth by Dr. Cady were published in Unity magazine. This material later was compiled into a book and it was the first book Unity published. It is now the most widely read book in that movement and it has been translated into eleven languages and braille.
Harriet Emilie Cady (1848-1941) was an American homeopathic physician and author of New Thought spiritual writings. She was inspired and influenced by Biblical teachings and the philosophy of Ralph Waldo Emerson. She was taught by Emma Curtis Hopkins, the New Thought "teacher of teachers" and a student of Christian Science. Cady associated with several prominent figures in the New Thought movement of the time and Charles and Myrtle Fillmore, co-founders of Unity Church.