As the ages of the world unfold, each brings its own character and challenges. In the Dvapara age, conflict begins to rise among beings, and with the coming of the Kali age, theft and dishonesty take root. Of all the ages, Kali is known as the most impure, its qualities and conduct shaped by the basest of the modes. Turning back to the earliest times, the Krita age—the age of perfection—endures for four thousand years, counted as human years. When these four thousand years draw to a close, a twilight period follows, marking the gradual end of the Krita Yuga. Once this twilight passes, the Krita Yuga comes to a complete end. With the passing of Krita, the Treta Yuga arises, bringing with it a new form of perfection. However, the eight perfections that flourished in Krita gradually begin to diminish, one after another, as the Yugas progress through all the cycles of creation and in each Manvantara. The twilight period of Krita, amounting to a quarter of the age, briefly holds sway before being overtaken by the new age. As the Yugas proceed, the virtues of austerity, learning, strength, and lifespan all decline. The Treta Yuga, at its origin, is only a partial reflection of the perfection that was present before. Yet, at the beginning of Treta, the world is still pleasant, and a new kind of perfection emerges even as the old is lost. During this time, something remarkable happens: from the clouds and thunder, a discharge begins to fall from the backs of beings. Trees become their homes, providing shelter and sustenance at the dawn of Treta Yuga. But the nature of things becomes fickle and suddenly changes, driven by the force of the Yuga itself. Then, as fate would have it, sexual union arises among beings, and conception begins to occur at improper times with the onset of menstruation. This change brings about the destruction of the trees that had served as homes. Yet, those who remain truthful in their intentions are able to attain a new form of perfection. Garments, fruits, and ornaments begin to appear, and a great power of inquiry awakens among people. Honey fills every cell, and, strengthened by this accomplishment, the people become free from illness. However, with this newfound abundance, people seize the trees and forcibly take honey and bees. The wish-fulfilling trees, along with their master, vanish from the earth. With this loss, pairs of opposites—pleasure and pain, heat and cold—arise among the people. Tormented by these dualities, they cry out and seek to cover themselves. Those who once wandered freely and at will now find themselves homeless once more, roaming the honey-laden peaks, mountains, and riverbanks, moving as they please across level and uneven ground. In response to their changing circumstances, they begin to construct villages and cities, carefully arranging their lengths, breadths, and internal layouts. It is at this time that measures and standards are established to bring order to their lives. Ten finger-joints are called a 'prādeśa'; the 'tāla' is remembered as the middle measure, and 'gokarṇa' as the smallest. A 'ratni' is counted as twenty-one finger-joints. Thus, with each age, humanity adapts and evolves, ever responding to the shifting qualities of time.