Which “heart” does the Heart Sutra actually refer to? The term “heart” in the Sutra primarily refers to the functions of the mind or consciousness (henceforth referred to as “mind”) that are not physical in nature. Based on its non-material functions, the mind can be broadly divided into the True Mind and the illusory mind. The True Mind refers to the mind of ultimate reality, while the illusory mind refers to the mind that arises and ceases. This book offers a brief overview of the relationship between the True Mind and the illusory mind. Heart Sutra-which heart does it refer to? It may not be what you think it is!