I'm a Swedish writer and instructor of the peaceful martial art aikido. I've written several books about qi and other lifeforce concepts. I'm also a historian of ideas, researching the thought patterns in creation myths. Google Profile. Here's my personal website: stenudd.com
The life energy exists in many traditions, such as qi (chi) in China, prana in India, pneuma in Ancient Greece, spiritus in Latin, and vitalism in philosophy. Here they are all explained.
Books by Stefan Stenudd:
The Greek philosophers and what they thought about cosmology, myth, and the gods, by Stefan Stenudd. Click the image to see the book at Amazon.
The Taoism of Lao Tzu Explained. The great Chinese classic, translated and extensively commented by Stefan Stenudd. Click the image to see the book at Amazon.
The ancient Chinese life energy qi (chi) explained and how to exercise it. Click the image to visit.
Taoism, the old Chinese philosophy of life, based on Tao, the Way. Click the image to visit.
Creation stories from around the world, and the ancient cosmology they reveal. Click the image to visit.
Life Energy Fundamentals
In traditional medicine, as far back as it can be traced, the bodily fluids have been given the most attention. Of primary conceren was the blood, since the loss of much of it would lead to death. Also, its distinct color must have made an impression on Homo rudis, as well as on each generation of mankind ever since.
Bloodletting (see the image of a medieval illumination) was the primary treatment of just about every illness in the Western medical tradition, all the way to the 19th century. And the doctors paid great attention to the hue of its color, its thickness, how fast it coagulated, and so on. Modern medicine, too, pays great attention to the blood, testing it to trace a vast number of maladies. It is indeed of massive importance in living bodies.
Traditional medicine also examined the other bodily fluids. Hippocrates (460-377 BC, see the image), the father of Western medicine, counted four of them: blood, phlegm, yellow bile, and black bile. He claimed that they had to be in balance, or the body would suffer some illness.
In other traditions, additional fluids have been given significance. For example, the tears were proof of human superiority over the beasts in the Christian tradition, since man seemed to be the only animal capable of weeping. Menstrual blood was regarded with awe, if not outright fear and condemnation, in many cultures - at least by their male population. Semen, on the other hand, has often been regarded as a substance of almost sacred might - again mostly by the males. Urine has been observed and utilized in traditional medicine and many household cures. And so on.
The importance given all those bodily fluids is probably linked to their motion. Life is movement, and Homo rudis could observe that the fluids moved constantly, so they had to be particularly enriched with life force, although not necessarily identical to it. They were carriers of it, in intricate patterns of streams inside every living body.
So, Homo rudis would easily come to the conclusion that the life force entered the body through the air, and then moved around in the body, carried by the bodily fluids. A dynamic system of movement, just as a force of life must behave.
BooksI have written two books on the subject of life energy: Qi: Increase your Life energy and Life Energy Encyclopedia. This website has material from the latter. Here are the two books: