Qi! So many ways to say something about it. I like a lot of what Jacob Godwin wrote in Acupuncture in Black & White: Qi, Yin-Yang, and the Cosmology of the Yijing:

“The Word ‘Qi’ is rather vague. It is primarily a way to refer to the ultimate medium of existence. This medium exists more fundamentally that the two states we call matter and energy because Qi can be both matter and energy just as water can be both hard and soft. The quality of the medium depends on which state it is in at the time of observation. We know now that matter and energy are, in fact, merely two aspects of one continuum. Einstein’s E=MC squared taught us that matter transforms to energy and vice versa. Just as energy and matter exist on a continuum, so do all other phenomena. Nothing is static here. Everything is on its way to being something else. Night is night becoming day, day is day becoming night, and so on.”