Kalpa (Sanskrit: कल्प kalpa) is a Sanskrit word meaning an aeon, or a relatively long period of time (by human calculation) in Hindu and Buddhist cosmology. The concept is first mentioned in the Mahabharata. Romila Thapar  holds that "the kalpa is first referred to in the inscriptions of Asoka". In the Pali (= early Buddhist) form the word kappa is mentioned in the assumed oldest scripture of Buddhism, the Sutta Nipata, where it speaks of "Kappâtita: one who has gone beyond time, an Arahant". This part of the Buddhist manuscripts dates back to the middle part of the last millennium BC.
Generally speaking, a kalpa is the period of time between the creation and recreation of a world or universe. The definition of a kalpa equaling 4.32 billion years is found in the Puranas—specifically Vishnu Purana and Bhagavata Purana.
According to Visuddhimagga, there are several explanations for types of kalpas and their duration. In the first explanation, there are four types:
- Ayu-Kalpa - a variable time span representing the life expectancy of a typical human being in a particular era or yuga. This can be as high as one asankya or as small as 10 years. This number is directly proportional to the level of virtue of people in that era. Currently this value hovers around 100 years and is continually decreasing.
- Antah-Kalpa - the time it takes for one ayu-kalpa to grow from 10 years up to one asankya and back to 10 years. The ending of one antah-kalpa (or mass-extinction) can happen in one of three ways, all involving the majority of the human population going extinct:
- Sashthrantha-Kalpa - Mass extinction by wars.
- Durbhikshantha-Kalpa - Mass extinction by hunger.
- Rogantha-Kalpa - Mass extinction by plague.
- Asankya-Kalpa - time span of 20 antah-kalpas. One is equivalent to a quarter of maha-kalpa.
- Maha-Kalpa - largest time unit in Buddhism. Ending of a maha-kalpa (apocalypse) can happen in three ways: fire, water and wind. It is divided into four quarters each equivalent to one asankya-kalpa.
- First quarter - time taken for this world to form.
- Second quarter - stable duration of this world where all living beings can thrive.
- Third quarter - time taken for this world to be destroyed.
- Fourth quarter - empty time period.
In another simple explanation, there are four different lengths of kalpas. A regular kalpa is approximately 16 million years long (16,798,000 years), and a small kalpa is 1000 regular kalpas, or about 16 billion years. Further, a medium kalpa is roughly 320 billion years, the equivalent of 20 small kalpas. A great kalpa is 4 medium kalpas, or around 1.28 trillion years.
Buddha had not spoken about the exact length of the maha-kalpa in number of years. However, he had given several astounding analogies to understand it.
1. Imagine a huge empty cube at the beginning of a kalpa, approximately 16 miles in each side. Once every 100 years, you insert a tiny mustard seed into the cube. According to the Buddha, the huge cube will be filled even before the kalpa ends.
2. Imagine a gigantic rocky mountain at the beginning of kalpa, approximately 16 x 16 x 16 miles (dwarfing Mount Everest). You take a small piece of silk and wipe the mountain once every 100 years. According to the Buddha, the mountain will be completely depleted even before the kalpa ends.
In one situation, some monks wanted to know how many kalpas had died so far. The Buddha gave the analogy:
1. If you count the total number of sand particles at the depths of the Ganges river, from where it begins to where it ends at the sea, even that number will be less than the number of passed kalpas.
In Hinduism (cf. Hindu Time Cycles), it is equal to 4.32 billion years, a "day of Brahma" or one thousand mahayugas, measuring the duration of the world. Each kalpa is divided into 14 manvantara periods, each lasting 71 yuga cycles (306,720,000 years). Preceding the first and following each manvatara period is a juncture (sandhya) the length of a Satya-yuga (1,728,000) years. Two kalpas constitute a day and night of Brahma. A "month of Brahma" is supposed to contain thirty such days (including nights), or 259.2 billion years. According to the Mahabharata, 12 months of Brahma (=360 days) constitute his year, and 100 such years the life cycle of the universe. Fifty years of Brahma are supposed to have elapsed, and we are now in the shvetavaraha kalpa of the fifty-first; at the end of a kalpa the world is annihilated.
Kalpa and other periods of time
"The duration of the material universe is limited. It is manifested in cycles of kalpas. A kalpa is a day of Brahmā, and one day of Brahmā consists of a thousand cycles of four yugas, or ages: Satya Yuga, Treta Yuga, Dvapara Yuga and Kali Yuga. The cycle of Satya is characterized by virtue, wisdom and religion, there being practically no ignorance and vice, and the yuga lasts 1,728,000 years. In the Tretā-yuga vice is introduced, and this yuga lasts 1,296,000 years. In the Dvāpara-yuga there is an even greater decline in virtue and religion, vice increasing, and this yuga lasts 864,000 years. And finally in Kali-yuga (the yuga we have now been experiencing over the past 5,000 years) there is an abundance of strife, ignorance, irreligion and vice, true virtue being practically nonexistent, and this yuga lasts 432,000 years. In Kali-yuga vice increases to such a point that at the termination of the yuga the Supreme Lord Himself appears as the Kalki avatāra, vanquishes the demons, saves His devotees, and commences another Satya-yuga. Then the process is set rolling again. These four yugas, rotating a thousand times, comprise one day of Brahmā, and the same number comprise one night. Brahmā lives one hundred of such "years" and then dies. These "hundred years" total 311 trillion 40 billion (311,040,000,000,000) earth years. By these calculations the life of Brahmā seems fantastic and interminable, but from the viewpoint of eternity it is as brief as a lightning flash. In the Causal Ocean there are innumerable Brahmās rising and disappearing like bubbles in the Atlantic. Brahmā and his creation are all part of the material universe, and therefore they are in constant flux."(Bhagavad-gītā As It Is 8.17)
Names of the Kalpas
The previous kalpa was the vyuhakalpa (Glorious aeon), the present kalpa is called the bhadrakalpa (Auspicious aeon), and the next kalpa will be the naksatrakalpa (Constellation aeon). Each kalpa has 1,000 Buddhas.
- Māheśvara and
The Vayu Purana in chapter 21 gives yet another list of 28 kalpas. It also lists five more kalpas in the next chapter.
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