(6.21) Sickness may be eliminated by placing ourselves in harmony with Natural Law.
We place ourselves in harmony with natural law by realizing that each individual is an outlet of Universal Power, which originates in Universal Mind. Practically, this means that all consciousness is recognized as originating from Self/Universal Mind, and all distinctions and prejudices are a result of ego identity. In addition, we understand that all experience is manifested by the Universal to facilitate collective Self Realization.
(6.22) Man is a spiritual being and this spirit must, necessarily, be perfect.
Thought is creative power and makes our species spiritual.
(6.23) A knowledge of this perfection-first intellectually, then emotionally-results in a manifestation of this perfection.
We may understand this perfection, first, intellectually. This is beyond a theoretical understanding because one can not really know something theoretically, they can only understand a concept. An intellectual understanding, necessarily, requires some kind of first hand observation/experience-be that in a lab, by crunching numbers, or encountering conditions in life. Once we have experienced something, we are able to feel an emotion regarding our experience. Feeling empowers experience and infuses it with value and meaning.