the universal cause.  The men of the Treta, the Dwapara, and the Kali Yugas are inspired with doubts.  The men, however, of the Krita Yuga are devoted to penances, possessed of tranquil souls, and observant of righteousness.[939] In that age all men regard the Richs, the Samans, and the Yajuses as identical not withstanding their apparent diversity.  Analysing desire and aversion, they worship only penance.[940] Devoted to the practice of penances, steadfast in them, and rigid in their observance, one obtains the fruition of all desires by penances alone.  By penance one attains to that by becoming which one creates the universe.  By penance one becomes that in consequence of which one becomes the puissant master of all things.[941] That Brahma has been expounded in the declarations of the Vedas.  For all that, Brahma is inconceivable by even those that are conversant with those declarations.  Once more has Brahma been declared in the Vedanta.  Brahma, however, cannot be beheld by means of acts.[942] The sacrifice ordained for Brahmans consists in japa (meditation and recitation), that for Kshatriyas consists in the slaughter of (clean) animals for the gratification of the deities; that for Vaisyas consists in the production of crops and, the keep of domestic animals; and that for Sudras in menial service of the:  three other orders.  By observing the duties laid down for him and by studying the Vedas and other scriptures, one becomes a Dwija (regenerate).  Whether one does any other act or not, one becomes a Brahmana by becoming the friend of all creatures.[943] In the beginning of Treta, the Vedas and sacrifices and the divisions of caste and the several modes of life existed in, their entirety.  In consequence, however, of the duration of life being decreased in Dwapara, those are overtaken by decline.  In the Dwapara age as also in the Kali, the Vedas are overtaken by perplexity.  Towards the close of Kali again, it is doubtful if they ever become even visible to the eye.[944] In that age, the duties of the respective order disappear, and men become afflicted by iniquity.  The juicy attributes of kine, of the earth, of water, and (medicinal and edible) herbs, disappear.[945] Through (universal) iniquity the Vedas disappear and with them all the duties inculcated in them as also the duties in respect of the four modes of life.  They who remain observant of the duties of their own order become afflicted, and all mobile and immobile objects undergo a change for the worse.[946] As the showers of heaven cause all products of the earth to grow, after the same manner the Vedas, in every age, cause all the angas to grow.[947] Without doubt, Time assumes diverse shapes.  It has neither beginning nor end.  It is Time which produces all creatures and again devours them.  I have already spoken of it to thee.  Time is the origin of all creatures; Time is that which makes them grow; Time is that which is their destroyer; and lastly it is time that is their ruler.  Subject to pairs of opposites (such as heat and cold, pleasure and pain, etc.), creatures of infinite variety rest on Time according to their own natures (without being otherwise than how they have been ordained by supreme Brahma).’[948]