The concept of an energy specific to living entities which is separate from that of inanimate matter is a very ancient one. It is the stuff of priests and priestesses, shamans and those involved in the occult (which means hidden). The earliest and most extensive coherent writings of any culture concerning energies and fields are those of India circa 5000 Before Common Era (BCE). An excellent account of the history and development of Yoga may be found in the book by Stephen Cope entitled "Yoga and the Quest for the True Self". Central to these writings are a concept named Prana. Prana is described as the energy which allows life to exist and which permeates all existence. Prana is described as having two polar opposites, the Ida and the Pingala, which when balanced allows for the expression of a third called the Sushumna. These three energies are said to be distributed to body regions through seven specific nodal points called Chakras. The energy of these seven chakras are redistributed to the specific body regions which correspond to these nodes through lesser points called nadis. The overall pattern of these nadi energies then allows for the continuous development and sustenance of the physical body.
The next thrust in human cultural development in relation to these subtle energies is in the Middle Kingdom (China) of about 3000 BCE, texts have been found which report on a universal energy called Qi (pronounced as chi or chee) which is found in all matter and the Chinese word for energy or life-force. Qi is said to have two polar opposites called Yin and Yang. The balance of Yin and Yang in the physical body is the basis of health. The Yin and Yang energies are said to be distributed in a continuous flow along channels called meridians. Any disruption in the natural flow of these energies along the meridians is then the cause of dis-ease. Qi Gong (pronounced chee-kung) is an ancient science in the Chinese medical tradition that has been developed and refined by Taoist masters in China for thousands of years. And, for thousands of years, it has been successfully used to maintain optimum health, treat and prevent disease, alleviate pain, and promote longevity. In a healthy body, Qi flows freely along the invisible paths called meridians. Adverse physical conditions, stress, or emotional tension may cause blockages or deficiencies of Qi which eventually lead to disease. With acupuncture, the doctor inserts sterile, disposable needles to open points along the meridians where Qi is obstructed. The Qi Gong physician uses his ability to manipulate Qi purely with his mind and breath. He not only opens the blockages but fills the meridians with fresh vital Qi. Classically, there are five expressions of these energies in the physical body which continuously cycle from one to another called Fire, Earth, Metal (Air is a newer term for Metal), Water and Wood which are described by Traditional Chinese Medicine (TCM).
Then in Greece about 500 BCE, writings appear describing a vital energy which may be likened to a luminous body. This energy is reported to be able to be manipulated by skilled persons to produce a cure in the sick.
During the Dark Ages in Europe, little survived of the rich medical heritage of the Egyptian and Greek cultures due to the overzealous efforts of the early christian bureaucracy. However, in the 1200s Common Era (CE) many forms of learning began to flourish again. The physician known as Paracelsus wrote about the Illiaster, a vital force and vital matter. This vital matter was reported to somehow allow life to exist. This vital force could be used for healing and spiritual work through the efforts of a skilled healer.
During the so-called "Age of Enlightenment" in Europe, the materialists gained the upper hand politically and with the aid of the Catholic church bureaucracy suppressed the vitalists. Science at that time described that all creation was a vast mechanism, even life. This bias in Science exists even today but signs of a new awakening from only a reductionist view to that of also a wholistic view is ever more evident. The truth will always prevail and is revealed to all those whom would but listen. Those persons whom do not know to not study a particular phenomena because it and they are outside the loop of established scientific dogma continue to discover for themselves the true reality of our physical existance. "The reality of existence trancends the vanity of man", Sunyananda Yogananda Saraswati.
During the 1700s CE, the work of one man concerning Subtle Energies stands out above the rest, in my opinion. Dr. Franz Antone Mesmer, a physician, wrote upon what he describes as the magnetic fluid which emanated at will from his hands during healing sessions. He could "charge" both animate and inanimate objects with this fluid which could then be used to affect healing in others.
During the 1800s CE, the work of Baron von Reichenbach is the next milestone in the description of the subtle energies. The Baron was a pre-eminent scientist of the day whom systematically studied for over twenty years what he termed the "Odic" force. This force was described in comparison with electromagnetism. More on the work of these two men follows.
As one may guess, the energies being described are the same but put into a different cultural aspect according to the knowledge and political atmosphere of the locale. This occurs in modern times as well as those whom "discover" for themselves these energies think that they are the new pioneers and name these energies something else out of ego and to attract the attention of the ill. In older times, as travel and information was not as prevalent as now, there is understanding as to the reason for this cultural naming. Today, however, it is due strictly to gross egotism and ignorance.
Today we recognize that the energies that these persons were trying to describe is a combination of metabolic processes, endocrine coordination, rheostasis (a more correct term than homeostasis) and most importantly, bioscalar energies. Scalar energies are what is left over if two similar energies move together in a linear fashion head on. The vector components of the waves cancel each other out and what is left is what is described by Physics as 'Scalar Energy'. Living organisms are able to do this trick and use this energy for whatever purpose suitable. This ability is what separates the Living from the Non-living!