sarva-dvaresu dehe ’smin
jnanam yada tada vidyad
vivrddham sattvam ity uta
"The manifestations of the mode of goodness can be experienced when all the gates of the body are illuminated by knowledge."
If we find three boys sitting or standing, we can identify who is sitting and who is standing. But such clarity is not found in the three qualities and so how to identify which quality is surfacing at a given time? Sri Krishna replies in this sloka and says that it was simple. Tada vidyad vivrddham satvam ity uta = then understand that satva guna has developed [on the surface]. When? Asmin dehe = in this body, jnanam = Gyana, prakasa upajayate = brightly shines, sarva dvaresu = from all thresholds [like eyes, ears, mouth, mind, etc., which are gyanendriya]. In these places the knowledge should shine brightly. Then only we can perceive a matter in its true perspective. Sri Krishna tells that whenever we are able to perceive through our organs, any matter in its proper perspective, then we can conclude that satva quality is prominent in us. Mind should think properly, like other organs. We find misunderstanding between father and son or mother and daughter, etc. If one is able to understand properly the intention of the other, then such misunderstandings will vanish. Sometimes, we misunderstand others with good intentions, because of the words used. If satva quality is prominent, then we will know the good intentions and avoid misunderstandings. Satva guna will avoid confusion between pillar and thief, rope and snake, etc. Clarity of perception is indicative of satva quality. Satva quality will wipe out the misunderstandings in the generation gap. When we visit Acharyas, we find they are able to understand our intentions. Anyone can become like an Acharya, if satva quality is developed and nourished. It is a self test. Whenever we find that we are clear in our perceptions, we should try to repeat those causing satva quality, like the food we ate. Similarly, we should avoid all those which induced rajo and tamo qualities in us.