Kālacakra
[[ |300px|thumb| ]] The Kālacakra (དུས་ཀྱི་འཁོར་ལོ་) teachings, which were introduced to Tibet sometime around 1027 by Kyijo Lotsawa and fully translated by Dro Lotsāwa Sherub Drak and Ra Lotsāwa Chorab (leading to two early lineages), had a major impact on the tantric tradition in Tibet. The most common historical tradition claims that the Kālacakra teachings were imparted by the Buddha in Dhānyakaṭaka stūpa on the full moon of the Caitra month (the third month in Tibetan calendar today) in the year after he reached full enlightenment. According to another tradition, the Buddha gave these teachings in the final year of his life. The teachings were dispensed to a large gathering of disciples, including King Sucandra of Śambhala kingdom. King Sucandra is said to have taken the teachings to Śambhala where it flourished for many centuries.
Seven generations later, King Yaśas, who is believed to have been an emanation of Bodhisattva Mañjuśrī, united the different subjects of his kingdom into a single Vajrayāna caste and composed the summarized version entitled Summarized King Kālacakra Tantra Extracted from the Supreme Primordial Buddha, commonly known as the Summarized Kālacakratantra, or Kālacakralaghutantra. His son, Puṇḍarīka, who is considered to have been an emanation of Avalokiteśvara, composed the commentary on the Summarized Kālacakratantra entitled Vimalaprabhā, or Stainless Light. The original Root Tantra, said to be 12,000 verses containing 384,000 syllables in length, is no longer extant, but many of its verses are cited in the Stainless Light.
The Summarized King Kālacakra and its commentary Stainless Light were first passed down to India from where it was taken to Tibet in the eleventh century. Since its arrival, the Kālacakra teachings have not only changed the Tibetan concepts of time and space and informed its calendar and cosmology but also impacted the understanding and practice of Vajrayāna Buddhism. The tantra, with five chapters discussing the concepts of external cosmology, internal sentient beings and energies, the rites of empowerment, instructions for deity yoga, and the cultivation of pristine wisdom, became one of the most encompassing and influential sources for Vajrayāna theory and practice and was embraced by all major traditions of Tibetan Buddhism, with many considering it a very advanced and superior form of tantric teachings.
The impact of the Kālacakra on the understanding of buddha-nature can be best seen in the explicit and emphatic teachings the Kālacakra text professes on the actualization of the blissful, empty, luminous nature of the mind, often referred to as the pristine wisdom of the fourth empowerment (དབང་བཞི་པའི་ཡེ་ཤེས་) and aroused through sexual yoga and control of energy fluids. It is this aspect of the Kālacakra teachings and the related sixfold yoga practices in the Kālacakra that inspired Dolpopa to rise as a strong advocate of other-emptiness and formulate an absolutist understanding of buddha-nature. It is this aspect that also aroused Mipam Gyatso to praise the Kālacakra as exceptionally effective in revealing the innate nature of the mind.
More on the link between buddha-nature and "the image of emptiness" (སྟོང་གཟུགས་) in the Kālacakra and other-emptiness can be found in Michael Sheehy’s presentation at the 2019 Tathāgatagarbha Symposium in Vienna and in Robert Thurman's explanation here.
Weekly quote
What is rigpa? The so-called rigpa is inner awareness free from conceptualisation. It is emptiness endowed with all aspects.~ Vimalaprabha
