4.27-28 Sarvani etc.  Dravyayajnak etc.  Again all the activities of their sense-organs,  the activities of their mind, and the activities of their vital airs,  such as issuing through the mouth  and nose,  driving down the urine etc., other  [seekers]  established  in the fire of concentration,  named  Yoga,  which is the means for subduing  the self i.e.,  the mind, and which is set ablaze by  i.e., to be filled  with, knowledge.  The idea is this :  With their intellect  that has completely abandoned  all other activities due to their  concentration on the object, they receive the object that is being perceived on conceived.  That has been stated in the  Sivopanisad :
 
'When the intellect,  concentrated on a certain object, not rejected, would not go to another object,  at that time the meditation, remaining in the core of the objects,  blossoms very much.'
 
Thus the Yoga-sacrifices are explained.
 So far the performers of the material-object-sacrifices, the austerity-sacrifices, and the yoga-sacrifices have been defined.  Those, who are the performers of the svadhyaya-knowledge-sacrifices are defined now [as] -