劉宗周（1578-1645）因《人譜》而有《讀易圖說》、〈易衍〉和《周易古文鈔》之撰著，因其「心學」而構架其《易》學哲學，彰顯出「即心即易，心易圓融」的「心易」哲學思想特徵。一方面，「以心解易，即心是易」。其一，易道居於聖人之一心，聖人之心即是「生生」之道體，由此可言「心外無道」、「心外無易」；其二，聖人善學天地，《易》為其階，聖人以一心印證天地之理，即心是《易》，《易》卦之象、爻體現了聖人之「心」；其三，聖人畫卦，以類萬物之情，聖人由「一」畫而作卦撰《易》，彰顯了「太極」、「兩儀」、「四象」、「八卦」、「六十四卦」生生不息之義。另一方面，「易以明心，心由易顯」。其一，「人心妙有，生生不已」，其本質便是「無極而太極」，是「生生之道」之顯現；其二，「先天後天，中和一體」，陰陽「順逆相生」，天道與地道統合，「先天」與「後天」打合，由此可推知「四德」與「四氣」是「中和一體」。自體而言，「心易」圓融，一體無礙；自用而言，君子用易，「《易》為君子謀，我心自治」：一方面，君子「尊心以神」，從而知微知彰；另一方面，君子「以變為要」，故能遷善改過。蕺山《易》學在心學視閾中展開，「心外無易」，要體思《易》道之精妙，須透視《易》所涵蘊之「心」，離「心」無《易》。同時，「心」體無處不在、無所不顯，《易》成為「心」「生生之道」得以彰顯的必然進程，學《易》用《易》便能彰明「心體」。

The Yi-ology of Liu Zongzhou (1578-1645), which is derived from the philosophy of heart/mind (xin) of the Renpu, represents the philosophy of the Yi jing through the study of the heart/mind. On the one hand, Liu Zongzhou considered that the heart/mind can be equated with Yi changes, and he illustrated Yi changes with the heart/mind. Firstly, the sages brought about Yi-ology to propagate the truth with the He tu and the Luo shu diagrams as foundations. The way of heaven was based on the Yi-ology stemming from the He tu scheme. The way of earth was based on the Luo shu configuration. Secondly, the sages created the Eight Trigrams with the heart/mind according to the study of the Yi jing. They kept the Dao of Yi changes in mind, studied the laws of nature with the assistance of Yi-ology, and created the Eight Trigrams to simulate all things and situations on the earth. On the other hand, Liu Zongzhou also suggested that Yi changes could cast light on the heart/mind. Firstly, the surface representations are often in contrast to the real heart. The heart/mind will manifest these representations of itself, and is always there. That is to say, “the mutual reinforcement and neutralization of each other” is consistent with the idea that “the great ultimate (Taiji) is in itself since there is no other organizing pole.” Secondly, the transcendental and the realistic are the same in the end. In other words, yin and yang are born as two opposing principles in nature with the purpose of unifying the way of heaven and the way of earth, the innate and the acquired. Then, the four virtues and the four qi could be balanced and integrated together. The Yi-ology of Liu Zongzhou proposes the idea of the integration of body and spirit, and Yi is the instrument according to which one becomes a profound person. The personalities of people with noble characters will be manifested when Yi is applied. People with noble characters value the heart/mind with divine respect and thus they see how things will develop from their first small beginnings. They attach importance to variations in order to reform and mend their ways to become good.