Bhagavad Gita, Chapter 4 verse 2Handed down in succession, one to the next, the royal sages understood  and experienced this Yoga. With the long lapse of time, the knowledge of Yoga  was lost to the world

Here, ‘Yoga’ means the practice of karma yoga, the way to instantly renounce action through action itself (4.01). In the eyes of Krishna the knowledge of how to achieve instant renunciation through the practice of karma yoga  is ‘imperishable.’ It is the nature of creation, the process of creation and in the imperishable nature of us (4.01). But after being ‘taught’ by Him, this knowledge was necessarily handed down from man to man with the inevitable loss of it: karma yoga was initially ‘taught’ in its pure nature by Him, then subsequently ‘declared’ and ‘told’ (previous verse). 

This regression in communication from ‘one to the next’ signals deterioration of understanding and degradation of experience. Maintaining both understanding and experience of renunciation requires spot-on faultless communication from one recipient to the next. Even the slightest misconnection will, over time, fully corrupt the teaching’s purity. 

Desire to achieve happiness in attractive qualities found in objects of the senses creeps in and bondage to action raises its ugly head (see endnote to the previous verse). Given that even the wise can be thrown off the path of evolution ‘by this insatiable flame of desire’ (3.39), maintaining purity of the teaching is a lot to ask of man, in fact, too much. ‘With the long lapse of time, this Yoga was  lost to the world.’ 

As if the knowledge of renunciation, which is the ‘eternal Yoga,’ was secretly hidden from view.