The human heart and the way-heart are attached.
Charting guides: Da Yan Yarrow Stalk Divination, Liu Yao Divination Chart
人心之危，《中庸》所謂誠之者也，所謂慎獨也；道心之微，《中庸》所謂誠者也，荀子所謂獨也。
The Shangshu · Da Yu Mo says "the human heart is only dangerous," which is exactly what the Zhongyong refers to as "the one who practices sincerity," that is, the practice of being cautious in solitude. It also says "the way heart is only subtle," which is exactly what the Zhongyong refers to as "the sincere person," that is, the state of "solitude" discussed by Xunzi. Hui Dong distinguishes "dangerous" and "subtle" as practice and essence respectively, which is different from the Song scholars' view that the human heart is human desire and the way heart is heavenly principle.
The distinction between sincerity and solitary action is attached.
誠之者，功之始也；獨者，功之全也。故荀子曰：「不誠則不能獨。」
"Cheng zhi" is the starting point of practice; "du" is the complete achievement of practice. Therefore, Xunzi says that without "cheng," one cannot reach the state of "du." Hui Dong here clarifies the sequence between the two: first there is the effort of "cheng zhi," and only then can there be the completion of "shen du." The two cannot be confused.
The study of birth and security is attached.
後人談孔學者止及困勉之學，未嘗不親切而有味，以示學者則善，以之訓詁六經則離者多矣。此七十子喪而大義乖之故，非後人之過也。
Later scholars who explained the teachings of the Confucian school only discussed the aspect of "knowing through hardship and acting with effort," which is indeed close and meaningful, and can be used to guide beginners. However, when applying this to explain the Six Classics, there are many places where it diverges from the original meaning. The Six Classics originally also include the aspect of "knowing by birth and acting with ease." This is due to the loss of the subtle and profound teachings after the death of the seventy disciples of Confucius, and not because of the faults of later generations.
The distinction between the refined and the crude is attached.
精者精微，一者道本。得一而加功焉，然後精。偽《尚書》「惟精惟一」，此誤解荀子也。吾聞一而後精，不聞精而始一，蓋後人以為精察之精，故誤耳。
"Jing" refers to the subtle and refined, and "yi" refers to the fundamental principle of Dao. One must first attain "yi," then work on it further, and only then can "jing" be achieved. The forged text of the Book of Documents, "The Great Yu's Mandate," says "wei jing wei yi," placing "jing" before "yi," which misinterprets Xunzi's statement. I have only heard that one must first attain "yi" and then be able to achieve "jing," never the reverse; perhaps later scholars took "jing" to mean the refined and meticulous, thus making a mistake.