The pineal gland or pineal gland (pineal gland) is an endocrine gland located in the center of the brain - the epithalamus: between the hemispheres in the area of ​​the interthalamic fusion.
This gland is called the pineal gland.
The existence of the pineal gland has been known since ancient times and even by ancient civilizations that lived on the planet many millions of years ago.

Hippocrates considered the brain to be the center of feelings and thinking, in which pneuma (PNEUMA) circulates.
Pneuma literally means “breath,” “breath,” or “spirit.”
In ancient philosophy and medicine, this term was used to refer to vital substance, air in motion, and in later contexts to refer to spirit or divine breath.
In ancient Greece, it was believed that pneuma, the spiritual-intellectual force associated with the breath of the first fire - the Logos, follows from ventricle to ventricle, and the pineal gland is a "gatekeeper", a valve on its path. It is a vital substance, necessary for life and movement.
In Western European medicine, the pineal gland was first mentioned and described as a valve by Herophilus of Alexandria.

The French philosopher and scientist René Descartes, in his treatises, especially in the treatise "Passions of the Soul" (Les Passions de l'âme, 1649) and "Treatise on Man" (Traité de l'homme), called the pineal gland (epiphysis) "Cartesian organ" - as the main organ of the location of the soul. His views were based on a dualistic philosophy that separates the mind (soul) and the body as two different substances.
Man is a being that combines two independent substances—material and thinking (spiritual). Descartes described the soul and body as two separate entities that are mechanically connected in man.

Rene Descartes described how two substances (thinking and material) meet in the pineal gland, which he called “the throne of the soul in the human body.” In his opinion, the pineal gland is a kind of “bridge” through which the soul influences the body, and the body transmits information to the soul.
The movement of the body is carried out thanks to "animal spirits" (esprits animaux) - subtle material particles that circulate through the nerves and muscles, like fluid in a hydraulic system.
The pineal gland, according to Descartes, controls the flow of these “animals.” The soul, by influencing the gland, changes the direction or intensity of their movement, which leads to physical actions or sensations.

The role of the soul

The soul, according to Descartes, is an immaterial, thinking substance that has free will and the ability to think rationally. Through the pineal gland, the soul receives signals from the senses and makes decisions, which are then implemented through the body.

Among the main functions of the pineal gland are:

• regulation of growth hormone synthesis and puberty;
• inhibition of tumor progression.
  The pineal gland affects the functioning of the entire endocrine system as a whole.