**Preface**

The *D. ak¯ ar¯ n. ava* ("Ocean of D. akas") is one of the last Tantric scriptures among ¯ those belonging to the Buddhist Sam. vara tradition. It consists of 51 chapters. As discussed in Section 2 in this monograph, it was developed sometime between the late-10th and mid-12th centuries, and the basic text of its extant version was most likely completed around the early 12th century in the eastern part of the Indian subcontinent (Bengal or Nepal). Chapter 15 of the *D. ak¯ ar¯ n. ava* (hereafter *D. ak¯ ar¯ n. ava* 15) teaches the principal man. d. ala of this scripture. It is a large-scale and elaborate man. d. ala of Heruka that comprises 986 major deities. The Lord or Blessed One (*bhagavat*), who teaches the *D. ak¯ ar¯ n. ava*, is named D. ak¯ ar¯ n. ava, Vajrad. aka, Heruka, ¯ S´akyasi ¯ m. ha, Kalacakra, etc. In the ¯ *D. ak¯ ar¯ n. ava* 15, the Lord is normally called Heruka.

This monograph presents the first critical edition, English translation, and annotations of the entire text of the Sanskrit *D. ak¯ ar¯ n. ava* 15, elucidates its structure and meanings, and clarifies its significance in the history of Buddhism in South Asia. I also provide the first critical edition, English translation, and annotations of the Tibetan translation of Jayasena's *Ratnapadmaraganidhi ¯* ("Precious Ruby Treasury"), a meditation manual for visualizing the man. d. ala of Heruka that is taught in the *D. ak¯ ar¯ n. ava* 15. Although no Sanskrit manuscript is extant, this text merits editing and translation. The *Ratnapadmaraganidhi ¯* is one of the oldest ritual manuals which has been composed based on the *D. ak¯ ar¯ n. ava*, and its author, Jayasena, was the leading specialist in this scriptural tradition in the 12th century in Kathmandu, composing several manuals (including the *Ratnapadmaraganidhi ¯* ) based on the *D. ak¯ ar¯ n. ava*. The Sanskrit of most of the passages in the *Ratnapadmaraganidhi ¯* can be restored based on the *D. ak¯ ar¯ n. ava* 15 and other related texts. This text is a good introduction to the *D. ak¯ arn ¯ . ava* system.

The discourses in most chapters of the *D. ak¯ ar¯ n. ava* are well organized. Although there are source texts based on which certain passages in the *D. ak¯ ar¯ n. ava* were composed, many of the passages in the *D. ak¯ ar¯ n. ava* are not mere copy-and-pastes or patchworks (with minor changes) of the source texts. The authors of the *D. ak¯ ar¯ n. ava* often reorganized and developed them into new systems. However, as is relatively common among Yogin¯ıtantra scriptures in the early medieval age, the language (Sanskrit and Apabhram. ´sa) used in the *D. ak¯ ar¯ n. ava* is in part "barbarous" (*mleccha* or equivalent) or non-standard. The text also contains many euphemistic terms, certain technical expressions, code words, which should not be interpreted only literally, and words peculiar to this scriptural tradition. Well-organized systems are present, or concealed, behind the barbarous and esoteric language. However, the text is thoroughly readable once one becomes accustomed to its language. I speculate that the anonymous authors of the *D. ak¯ ar¯ n. ava* were fully aware of what they were editing. They composed the text, often utilizing transmissions whose Sanskrit was already in part broken as sources, using the language and esoteric terms with which they were familiar, and, possibly, deliberately applying the non-standard form of Sanskrit to make the text more esoteric.

In editing the text, I have not adopted the assumption that there was an urtext of the *D. ak¯ ar¯ n. ava* that was composed (entirely or mostly) of the standard form of Classic Sanskrit. The peculiarities of the language used in the *D. ak¯ ar¯ n. ava* can also be attested in some of the parallel passages found in the texts that antedate the *D. ak¯ ar¯ n.* ava and in most parallel passages present in the texts that postdate the *D. ak¯ arn ¯ . ava*.

In the last stage of the history of Tantric Buddhism in India, when various Buddhist Tantric traditions were already present, some encompassing texts were composed, such as the *Kalacakratantra ¯* (the early 11th century) and the *Vajraval ¯ ¯ı* of Abhayakaragupta (between the late 11th and the early 12th centuries). These ¯ texts provide inclusive Tantric systems into which various preceding traditions were integrated and reorganized. Although it was not so influential as the *Kalacakratantra ¯* and Abhayakaragupta, which is, I speculate, partially due to its peculiar language, ¯ the *D. ak¯ ar¯ n. ava* is also one such text. I will clarify that the Heruka man. d. ala in the *D. ak¯ ar¯ n. ava* 15 is a comprehensive system that integrates various Tantric traditions and components of the Buddhist cosmos within the framework of the Sam. vara system. This monograph will thus elucidate an aspect of the last stage of the history of Tantric Buddhism in India.

I will provide a critical edition and translation of some of the other chapters of the *D. ak¯ arn ¯ . ava* in the near future.

> Tsunehiko Sugiki *Hiroshima University Higashihiroshima, Japan*
