Duality of Mind

The conscious and the subconscious.
The objective and the subjective.
The waking and the sleeping.
The voluntary and the involuntary.
The outer and the inner.

The subconscious is subject to the conscious.
Hence the terms subconscious or subjective.
The subjective mind is subject to intuition, emotions, memory and has the capacity for clairvoyance and thought reading.
It is subject to the information you give it.
Your habitual thinking steers your subconscious.

The conscious mind is the objective mind because it deals with external objects.
It uses your five physical senses.
It learns by observation, experience, education and reasoning.

Thomas Troward used the terms objective and subjective.
P.P. Quimby used his own terminology. He also used his own terminology to describe the ego. Freud hadn't invented that term yet.