One thing the de teaches, is simply to be quiet. Relating to energy, when learning to sink qi to dantian, we just have to watch in alignment as the body remains still, with practice can see/feel the settling down, like the glass of muddy water becomes clear only if you stop trying to stir it up.   For the intellectually thirsty, or just bored, this essay looks  pretty promising: The Concept of de ("Virtue") in theLaozi   It's funny, as i'm reading through it, can watch as the light slowly reaches back out, to entangle with the words, and bounce them around in the noggin. Then take a break and look back to the lower dantian, remembering a Damo Mitchell talk i recently watched on youtube, where he likened the qi to an elderly on a walker, slowly catching up to wherever the mind jumps to at will. Or like molasses being poured, good things come to those who wait.