The research undertaken here about Buddhist mandalas is basically designed under the philosophical question how the visible dimensions of forms are related to their invisible contents. The textual sources in reference to Buddhist mandalas teach that the essence of mandalas is shunya (void) and their forms are the reflective images (pratibimba) of shunya. This volume investigates how the colourful form of Buddhist mandalas represents the prime concept of shunya, and what makes these mandalas visually powerful, leaving the impression of “spiritual enhancement” in the heart of people who do not even know about the Buddhist doctrines. The mandalas permanently represented in the monastic complexes of Tabo and Alchi in the Western Himalayas have been focused in order to examine a prominent role of visual dimensions of mandalas. In order to comprehend mandalas in the context of Buddhist philosophy, the texts of the Yoga-Tantra class have been looked up. Especially, the references to the tantric visualization-practice throw light on the internal experiences with mandalas. Considering the fact that the Buddhist mandalas have been developed as a method of Mantrayana, being always combined with mantras and mudras, this volume presents the concept of vak (word, subtle sound, voice) as a key to explain how the ultimate state of shunya and perceptible forms of mandalas are related to each other. The doctrine of vak developed in the tradition of Trika Shaivism in Kashmir provides us with a systematic way to explain the non-dualism between all phenomenal objects and the Supreme Divine. The doctrine of four levels of vak is examined in the book for the purpose of interpreting the aesthetic phenomena and structuring the different levels of meanings of mandalas from the aesthetic perspective. On the basis of the vak theory, the external forms of mandalas have been explored and their visual principles have been technically analysed, in attempt to answer the question: how do the colourful forms of Buddhist mandalas resemble the formless shunya?