Śrī Kṛṣṇa Himself has enumerated the basic principles of a caste system that is real and universal. The four social orders (intellectual, administrative, mercantile, and laborer) are set by Him according to the qualities these persons have acquired through their actions under the modes of nature. So although in one sense He is the maker of this caste system all over the world, still, in another sense, He is to be understood as not its maker. That is, He is not the maker of a tyrannical and unnatural caste system in which the faithless dictate one's position according to one's birth. Rather, He is the maker of a caste system that is applicable universally, is voluntary and natural, and is based on one's qualities and abilities.
The four social orders—generally known as the "caste system" and consisting of the brāhmaṇas (priests and intellectuals), the kṣatriyas (administrators and soldiers), the vaiśyas (merchants and farmers), and the śūdras (laborers)—were never meant for a caste system by birthright. This system is universally applicable in terms of one's mundane, practical qualifications and personality traits. The classification of brāhmaṇa, kṣatriya, vaiśya or śūdra is never made with reference to one's accidental birth—any more than someone could become a medical practitioner by some mere birthright, simply because he happened to be the son of a noted doctor. The real qualification of a medical practitioner can be obtained only through strenuous study of medical science for a considerably long period, and only upon completion of his studies can he take up the medical profession. Naturally, when a patient goes to a medical practitioner, he does not look at the birthright of the physician, but at his real, professional qualifications.