Carl Jung, along with Freud, Skinner, Rogers, etc founded the study of the soul from a secular and medical position. For thousands of years the psyche had been the arena of Hebrew and Christian Priests as well as Buddhist and Muslim Teachers. Then, the mental and emotional issues faced by all humans became the interest of Physicians.
But Jung, like many, cam to the field as a person that has struggled mightily with his own deep struggles. He is quoted by Lisa Marchiano as writing in his book Memories, dreams, reflections,