修行者修行目的，在斷盡凡人的塵勞妄想，與轉化滌除原始無明心性，這與習慣領域學說的核心思想有密切相關，本文以此探析虛雲老和尚展現的大HD。虛雲是民國以來奇聞異事傳說最多的一位得道高僧，身兼禪宗曹洞、臨濟、雲門、法眼、潙仰五宗法脈，他的修行理念是解行並重、禪淨兼併，強調守戒持律；他一生表現出來的大HD，是菩薩大修行者的格局與視野，心堅行苦，行人之所不能行，忍人之所不忍，藉事驗心，藉境煉心，完成許多常人所不能完成的志業與壯舉；他泯除一切分別、對待，苦樂俱捐，沒有此岸、彼岸之分，行住坐臥都在禪定中，展現「應無所住」修行最高境界，世間就是度人濟世的道場，煩惱就是菩提種子，他的實際領域就是開闊恢弘的潛在領域，完全超越世人眼界與作為，展現菩薩般的大HD。

The goals of a Buddhist Dharma practitioner are to overcome worldly illusions and vain hopes, and to convert and cleanse the original mind. These are similar to the core ideas of Habitual Domain theory, which thus becomes the major theory employed in the present study of Master Hsu Yun. Master Hsu was the most fabled of the great monks who attained enlightenment after the establishment of the Republic of China. He practiced the teachings of the five Zen sects: Cao Dong, Linji, Yun Men, Fa Yen, and Wei Yang. His practice of Dharma shows that he places equal weight on theory and practice and combines the rituals of both the Zen and the Pure Land schools of Buddhism. He also emphasizes following precepts and rules. The great Habitual Domain displayed throughout Hsu Yun's life illustrates the general status and vision of a masterful bodhisattva practitioner. Master Hsu was resolute and lived an ascetic life. He tested and explored his mind through experiences of the secular world. He ignored distinctions and privileges in his approach to the world, going beyond bitterness and joy as well as the artificial separation of the enlightened and the mundane, in his perception of reality. He remained in a state of meditation in all acts of his daily life, demonstrating the highest realm of Dharma practice (i.e., the state of a carefree mind), and arguing that the mundane world was a meditation hall to deliver and save the people, and worldly worries were the seeds for Bodhi enlightenment. Master Hsu Yun's Actual Domain is the expansive realm of a human being's Potential Domain, which completely transcends the vision and acts of the worldly, showing the great Habitual Domain of a bodhisattva.