The duality of mind.
You have only one mind, but your mind possesses two distinctive characteristics. The line of demarcation between the two is well known to all thinking men and women today. The two functions of your mind are essentially unlike. Each is endowed with separate and distinct attributes and powers. The nomenclature is as follows: The objective and subjective mind, the conscious and subconscious mind, the waking and sleeping mind, the surface self and the deep self, the voluntary mind and the involuntary mind, the male and the female, and many other terms. You will find in terms “conscious” and “subconscious” used to represent the dual nature of your mind throughout this book.
~ Joseph Murphy, The Power of Your Subconscious Mind(1963)