Complex sentence: Boehme was an advocate of personal wellness through transformative thought, and all of her books dealt with to a greater or lesser extent with personal experiences of health and healing that she said were achieved by application of New Thought principles.
Split into simpler sentences: Boehme was an advocate of personal wellness through transformative thought. All of her books dealt to a greater or lesser extent with personal experiences of health and healing that she said were achieved by application of New Thought principles.