The Treatise of the Sun

original: "Surya Siddhanta"

The result is that two Kalpas A Kalpa is a "Day of Brahma," equal to 4.32 billion years constitute his day and night. || 20 || Now, the author describes the total lifespan of Brahma and the amount of time that has already passed.

His total lifespan is one hundred years, measured by those days and nights.

Half of his life has already passed; this current Kalpa is the first of the remaining half. || 21 ||

Listen to the supreme truth—you have heard what was said before, and now listen to what is about to be said. Alternatively, "Supreme" original: "Parama" is an address to the Great Demon The Surya Siddhanta is traditionally revealed to Maya, a great architect and asura/demon. You should know that the lifespan of Brahma is one hundred years, measured by the aforementioned "day and night" consisting of two Kalpas. This is the meaning: from the measurement of a day and night, a month is calculated according to the previous definitions, and from that, a year of Brahma is calculated. One hundred of such years is the lifespan of Brahma.

It does not mean a literal hundred days, for even insects are not said to have a lifespan of only a hundred days; therefore, it is impossible for Brahma to have a lifespan of only a hundred days.

This is also stated in the Vishnu Purana A sacred text detailing Hindu cosmology and mythology. By this, the idea of a "short" supreme life is refuted, as it is impossible for Brahma to have an indefinite or short lifespan. Half of Brahma's life—amounting to fifty years—has passed. This current time is the first "remaining" Kalpa; the result is that this is the first day of the second half of his total life expectancy. || 21 || Now, he describes what has passed within this current day.

In this Kalpa, six Manus with their respective twilights have passed.

Of the current Manu, Vaivasvata, twenty-seven Great Ages have passed. || 22 ||

A "Manu" is a progenitor of humanity who rules over a Manvantara, a period of about 306 million years. We are currently in the era of the seventh Manu, Vaivasvata.