The work presents a profound and far-reaching analysis of the ideas, religious aspirations and building techniques which contributed to the creation of one of the largest Buddhist edifices in the world. This book is not a history of the famous Javanese monument nor is it a history of Buddhism. It is the English translation of the foreword to a work - loosely focused on the Barabuḍur - which was published in Hanoi in French (1935). Besides, it is a survey of the Buddhist religious and philosophical concepts in the background of earlier religious and metaphysical traditions in India, as revealed in the Vedic and Upaniṣadic texts.