Caste is a poor choice of word to translate the concept of Society, as it implies permanence where none exists: the migration of an individual through the four Ashramas and four Societies (total: sixteen Societies of Ashrams) is as much part of life as the migration of an individual through the numerous Worlds (lokas) of Samsara. Unlike the migrations through Samsara, the migration through Society leads to the freedom from suffering. Nevertheless, the term "Caste" has become common nomenclature.
The Brahmans, Kshetriyas, Vaisyas, Sudras: when practicing in the Ashram of Vanaprastha, individuals within all these societies develop by their loyalty to duty a greater society. By loyalty a person comes to understand their duty and responsibilities. But they also come to understand the importance of imperfection: just as devout loyalty to a spouse reveals the numerous imperfections of both spouses while strengthening the love shared between those spouses, so too do the devotions to Caste reveal imperfections in the Caste, and in the Castemember.
When a person serves society to the extent of their ability, temperament, taste and capacity, they develop sufficient politeness and courtesy to civilize themselves. They begin to see their own face in those faces of their neighbors, and understand the co-dependency and co-origination of all phenomenon; veneration naturally develops into sacred worship. Such loyalty helps a person transfigure themselves from the destiny and caste of their birth into that of the ultimate human potential.
The commercial service of a Sudra leads to industrial productivity of a Vaisya, the industrial productivity of a Vaisya leads to civil prowess, splendour, firmness, dexterity, bravery, generosity common among Kshetriyas. This lends itself to the development of a noble and royal nature. Such ennobling when perfected by loyalty leads to a Brahman's serenity, self-restraint, austerity, purity, forgiveness, uprightness, wisdom, knowledge and profound understanding.
The Buddha Gotama, an Avatar of Vishnu, taught that it is not by birth that one is a high caste, a "supreme man," a "superman," a Brahman, praised by Indra and Brahma. Through self-control and righteousness one becomes a better person. He and countless squadrons of Liberators restored the Dharma by restoring society: they freed every being to pursue this self-improvement required for the freedom from suffering, enlightenment, and then final knowledge.
You can join their effort - join our effort - in Loka Hatha Yoga to the restoration of society.
The Puranas say that people once worshiped the sun, understanding it was the sustenance of their existence. But in the darkness of the world, deprived of their sustenance, those beings who were inclined toward rightness embraced the ritual sacrifices, those inclined toward wrongness rejected the ritual sacrifices, those inclined both to right and wrong undertook the sacrifices with doubt, and those inclined neither to right nor wrong gave cause, action to the sacrifices.
As a new day arose, a new age arose, the nature of humanity evolved. Those inclined toward rightness developed goodness; those inclined toward wrongness developed wickedness; those inclined both to right and wrong developed courage; those inclined neither toward right nor wrong developed a true humanity, and a nature independent of Brahma, maturing into a new being. As the day rose, Brahma observed, and then described the Dharma of people, understanding that duty had evolved.
Brahma noticed, too, that all the other beings of the universe had similarly grown. These other beings took interest in the affairs of each other, and inclined toward shared nature, took society with each other. The dead ghosts found society with the good Brahmans, the devas found society with the brave Kshetriyas, the spirits of the world found society with the Sudras, and so forth. And in society, these beings together assumed control over regions of the world, every loka knew mastery for the first time. And their duties in these lokas guided them into systematic organization, cooperation, and co-dependence. From the deepest reaches of Hell to the highest reaches of Heaven, every being was observed by Brahma, who described the Dharma observed.
But as the ages past, these beings strove with each other, and in fighting, caused each other harm, conquering and occupying other worlds which neither belonged to them, nor where they belonged. There was great distress; the worlds themselves grew blurred in difference and distinction. Vishnu was called upon to restore society, to restore the worlds. Manifesting as the Buddha Gotama, he taught the means by which we may either find our world, or come to belong in the world we now occupy. Gotama taught the means by which to end our distress. As a person might change their clothes in the morning, or in the afternoon, or the evening to suit the needs of the place or occasion - so may anyone attain the comfort they require by strength of mind, heart and body.
Throw down your burdens, and meditate upon the cause, the nature, the ending and the way to the ending of distress. Follow the instructions of the Buddha Gotama: then conquer, just as he, the Conqueror, had once conquered! Like him, remember all your previous existences, and then purify yourself. Burst through the mass of darkness like the sun!