4.29-30 Apane etc.  Apare etc.  Prana  (1st)  :  the arising  one i.e.,  the nada which has, as its end, that one where the first syllabic instance of  Pranava  dissolves.   Into the apana : into  what sets down,  and is of the nature of entering  inot the Svananda.  They offer :  Thus is the svadhyaya of the nature of the firmness of the body is described.
 
What sets down, some  [sages]  established on what rises up,  so that the pupil's  self  (mind)  may learn the processes of sending out and drawing  in [the vital airs].  By [thus]  uniting  these two, they bestow emanciaption on their own Self  and on the Self of the pupils;  and they,  on that account, remain with their mind firmly established on the svadhyaya-sacrifice full of Svananda  (i.e.,  Nijananda) and Parananda - a svadhyaya of the nature of examining,  enlightening, entering and uniting  [the prana nad apana]  in their own Self  and in the Self  of the pupils.  That is why the process of filling  [the vital air] in has been first  mentioned;  and the process of  emptying the same out at the last.  Further, the process of the inward turning of the act of enjoying objects, is  suggested by the first  arter of the verse (29),  and by the second  arter the act of coming  out for enjoying  the objects through the process of having the supreme state-of-bodylessness.  Therefore,  the performers of the sacrifice of wisdom are not different  from the performers of the svadhyaya-sacrifice.
 
The same sages have the desries of  their  own and of their pupils fulfilled  on  account  of their  thorough practice of the said  activity;  control both the said  paths, restrict their food viz.,  enjoyment of objects;  and offer pranas  into the pranas, i.e,  they offer, by means of the ietude at the stage  of stopping  [the vital air],  the rising  of all the mental modifications into the splendour of rising waves  of  Parananda and  Nirananda.  All these persons  know the truth (or nature) of hte sacrifices, starting from the material-sacrifice upto the wisdom-sacrifice;  only by that means they have eradicated their sins; that is to say,  they have uprooted the mighty delusion with its roots,  made of mental  impressions of duality.