Nervous and Psychic Power is seated inside the brain and is constituted by two powers -
a) Quwat - e - Mudrika (Perceptive power) which conveys impressions or sensation.

b) Quwat - e - Muharrika (Motive power) which brings about movements as a response to the sensation.

c) The Unani system of medicine has also emphasized the states of body and pattern of diseases. According to Galen, the human body has 3 states, namely

• Sehat - Health
  
• Marz - Disease,
  
• La-Sehat-La-Marz - Intermediate State, which is called as Hazla-le-Salaasa

Sehat - (Health):
It is a state in which the Temperament and structure of the human body are such that all its functions are carried out in a correct (saheeha) and whole (saleemah) manner.

Marz - (Disease):
It is an abnormal state of human body which primarily and independently but not secondarily, disturbs normal functions. Diseases may, thus, be a disorder of Temperament, humoural imbalance or structure.

La-Sehat - La-Marz (Intermediate state):
The third state according to Galen is the state of neither health nor disease i.e. here, there is neither perfect health nor any definite disease, as in the case of old age, convalescence and infancy or, during incubation (Muddate-Hizanat).