In Cause and Effect (address of 1929) he writes about God as the only Cause. Understanding spiritual cause and effect is at the heart of our work in Christian Science. Material cause seems to operate as law in a material universe, but if God is all, there can be only one cause and that is the divine Principle, Love. Mr. Greenwood explores this idea from many angles, explaining the impossibility of a negative cause and an evil power. He tells how evil is an illusion that cannot invade consciousness if we are holding to the fact that God is All. He urges and pleads with us to “take the stand that God is all there is or can be.” Regardless of the imperfection and discord the senses may be telling us, God alone is real. He writes, “Every problem which faces us calls for healing — that is, for an improved sense of God. It is the absolute or perfect truth about God and man, not a partial or fragmentary statement, which heals. Your thinking must take in the perfect Principle of things, the Truth of perfect being, perfect cause and perfect effect, perfect Principle and perfect idea. The cause alone governs the effect. We must begin all our work from that starting point and hold to it all the way.” This address is a strong treatment on the allness of God and the absolute unreality of evil.