From the upcoming 6th edition of 21st Century Science and Health:

Question. What is the scientific statement of being?

Answer. There is no life, truth, intelligence, nor substance in matter. All is infinite Mind and its infinite manifestation, for God is All-in-all. Spirit is divine Truth; matter is human error. Spirit is the real and eternal; matter is the unreal and temporal. Spirit is God, and we are Spirit’s image and likeness. Therefore person is not mortal, but is immortal.

Question. What is substance?

Answer. Substance is that which is eternal and incapable of disorder and decay. Truth, Life, and Love are substance, as the Scriptures use this word in Hebrews: “The substance of things hoped for, the evidence of things not seen.”[1] Spirit, the synonym of Mind, Soul, or God, is the only real substance. The spiritual universe, including individual persons, is a united idea, reflecting the divine substance of Spirit.

Question. What is Life?

Answer. Life is divine Principle, Mind, Soul, Spirit. Life is without beginning and without end. Eternity, not time, expresses the thought of Life, and time is not a part of eternity. You know Life when you stop knowing time. Time is finite; eternity is forever infinite. Life has nothing to do with boundaries of any kind. Spirit doesn’t know the stuff called matter. Soul includes in itself all substance and is Life eternal. Matter is an incomplete human concept or invention. Life is divine Mind. Life is not limited; death and limitation are unknown to Life. If Life ever had a beginning, it would also have an ending.

Question. What is intelligence?

Answer. Intelligence is omniscience, omnipresence, and omnipotence. It is the primal and perpetual quality of infinite Mind, of the all-inclusive Principle—Life, Truth, and Love—named God.

[1] Heb. 11:1 (NKJV)