Thergana does not mean vitantic knowledge. It means the simple conscience, this is right and that is wrong,. What art we have learnt from society that we don't follow? We are strong likes and dislikes. And because of more delusion. Delusion means that which is er right seems to be not worth it, or wrong. That which is wrong seems to be right. This is just a little diversion. I'm telling you it very nice insight, which i got from asado. Of course, the topic here is not meditation. But iam still bringing it up here. Upper ritagana, how this works? Oga sutras t tell us.