Harriet Emilie Cady was an American homeopathic physician and author of New Thought spiritual writings. Her 1896 book Lessons in Truth: A Course of Twelve Lessons in Practical Christianity is now considered one of the core texts on Unity Church teachings. It is the most widely read book in that movement. It has sold over 1.6 million copies since its first publication, and has been translated into eleven languages and braille.