This is a somewhat old-fashioned construction.

_noch_ translates to _still_ or _yet_ and _stets_ is a somewhat old-fashioned (but still in use) form of saying _always_ or _ever_.

_noch immer_ or _noch stets_ is signalising that the speaker is anticipating dissent on their claim. The sentence could be translated as follows into English:

> Yet, the eagle has always wasted its time when wanting to learn from the raven.

This is not a perfect translation, since the starting _yet_ seems a bit unmotivated, since there is nothing it refers to. In the German construction _noch stets_ or _noch immer_, this is suggesting that the speaker anticipates dissent, and still believes their claim to be true.