Born in 1848 as Harriet Emilie Cady in a farmhouse in Drysden, Syracuse, a beautiful and prosperous part of upstate New York, she was the daughter of a hardy pioneer. In her book How I Used Truth Cady relates that her father was well known and respected in their neighbourhood. Cady soon dropped the name Harriet, preferring Emilie. She spent the early part of her career in her hometown as a schoolteacher in a one-room schoolhouse.

Emilie Cady eventually chose a career in medicine in the 1880s, a field that even 120 years later is still dominated by men. She was as an established and successful physician that she first appeared on the Unity scene.

When her booklet Finding the Christ in Ourselves came to the attention of Myrtle Fillmore, she gave it to her husband, Charles Fillmore, who lost no time in asking permission to print and distribute the booklet and invited her to write for Unity Magazine. As a result, beginning in 1892, a number of articles by Dr. Cady appeared in the magazine and she later went on to write the Unity textbook, Lessons in Truth which was translated into eleven languages and braille. From all over the world, from the length and breadth of the continent, letters came, testifying to lives transformed, physical ailments healed, money problems resolved, domestic difficulties dissipated, all through the study of her inspired book and the application of the principles therein.