熊十力認為孔子《周易》有其理論基準，而此亦即熊氏《易》學之「理論設準」也。熊氏從破除古術數家與漢《易》家之迷謬，以揭出其要義。古術數家信有天帝，此其兩大根本信念之一，孔子則「以乾元取代天帝」，即明白廢除天帝，從而揭示乾元。古術數家之言陰陽則云二氣，此乃根據信有天帝之迷謬而來，孔子則「以乾坤兩大勢用取代陰陽二氣」，即以乾為生命、心靈，坤為物質、能力，乾坤乃兩大勢用，以取代陰陽為二氣之說。熊氏且又歸納孔子《周易》之制作凡例，認為古術數家為占卜而取象，不免失之雜亂，孔子則改象為譬喻，即假象以顯此理而已，並更歸納出若干「義例」，此象與義例，實為悟入《周易》之鎖鑰。故務須明瞭以上各理論基準，則於熊氏「體用不二」論必可瞭然無遺。

Hsiung Shih-li considers that there is a theoretical foundation in Confucius' "Chou-I." This concept also becomes Hsiung' "The Theoretical Assumptions" of "Yi" study. By breaking the myth of the ancient astrologists and "Yi" study of Han School, Hsiung attempts to reveal the true meaning of "Chou-I. " The ancient astrologists believed in the Supreme Being in the universe. Such a belief is one of their two basic principles. But Confucius' opinion is "to replace the Supreme Being by Ch'ien Yuan." By saying this, he clearly manifests his assertion to abolish the belief in the Supreme Being and present the idea of Ch'ien Yuan. In the viewpoints of the ancient astrologists that originate from the belief in the myth of the Supreme Being, yin and yang are two kinds of energy while Confucius holds different opinion to "replace yin and yang by the two great applications of Ch'ien and K'un" in which Ch'ien is for life and mind; and K'un for materiality and power. Hsiung alsogeneralizes the making of examples in Confucius' "Chou-I." He thinks that the ancient astrologists choose the signs to divine but this method easily results in a state of disorder. So Confucius changes signs into metaphors, that is, to use signs to illustrate the interpretation; moreover, he further induces them into certain semantic categories. The study of signs and semantic categories is truly the key to comprehend the text of "Chou-I." It is a must to understand the theoretical foundation above so that Hsiung's theory of "unity in essence and action" can be fully appreciated.