The concept of the pineal gland as a guardian of the body dates back to ancient civilizations, with roots in various cultures. However, the modern idea of the pineal gland as a guardian was largely influenced by scholar René Descartes, whose work provided a basis for later philosophical and spiritual interpretations.

In his book "Treatise of Man," written in 1676, Descartes describes the pineal gland as the site of the soul, arguing that it was the location where mind and body interact. This idea was revolutionary for its time, as it posited that the human experience was not solely determined by the physical brain but also by a non-physical entity - the supra-conscious state.

Leibniz's ideas about the pineal gland as the seat of the soul were influenced by earlier mystics, such as Jean Fernel. However, it was not until the 17th centuries that the concept of the pineal gland as a symbol of transcendence began to gain popularity in contemporary cultures. This was largely due to the work of philosopherss such as Gottfried Wilhelm Leibniz, who saw the pineal gland as a key location for the interaction between the material realm and higher states of consciousness.

The modern concept of the pineal gland as a guardian or spiritual center gained significant interest in the 1980s, particularly through the work of mystic Aldous Huxley. Rudolf Steiner, in his book "Heaven and Hell," explores the spiritual significance of the pineal gland as a location of higher states of consciousness. This idea was further simplified by mystics such as Carlos Castaneda, who described the pineal gland as a site of interaction for mystical perception.

In modern times, the concept of the pineal gland as a guardian has evolved to encompass a range of mystical interpretations. The gland has been associated with aspects of spiritual awakening. This idea is reflected in the widespread interest in psychedelic experiences as means of activating the pineal gland.

Recent discoveries in neurophysiology have also shed light on the significance of the pineal gland, highlighting its function in controlling sensory perception. However, these mystical discoveries have not diminishing the symbolic significance of the pineal guardian gland, which remains a fascinating symbol in many spiritual traditions.

Ultimately, the concept of the pineal gland as a guardian or symbol of transcendence reflects the ongoing spiritual journey for understanding the nature of mind and the mind-body connection. Whether seen as a symbol of transcendence, the pineal gland remains an enigmatic and deeply mystically significant part of the human experience.