A tiny little structure deep in my brain that I never heard of until a tumor was discovered on mine. What is a Pineal gland? The answer to that has changed over the years. Hopefully we are closer to the correct function of that gland than they were in the past. There’s some ancient information here but I found it fascinating.

1. Pre-Cartesian Views on the Pineal Gland

The pineal gland or pineal body is a small gland in the middle of the head. It often contains calcifications (“brain sand”) which make it an easily identifiable point of reference in X-ray images of the brain. The pineal gland is attached to the outside of the substance of the brain near the entrance of the canal (“aqueduct of Sylvius”) from the third to the fourth ventricle of the brain. It is nowadays known that the pineal gland is an endocrine organ, which produces the hormone melatonin in amounts which vary with the time of day. But this is a relatively recent discovery. Long before it was made, physicians and philosophers were already busily speculating about its functions.

1.1 Antiquity

The first description of the pineal gland and the first speculations about its functions are to be found in the voluminous writings of Galen (ca. 130-ca. 210 AD), the Greek medical doctor and philosopher who spent the greatest part of his life in Rome and whose system dominated medical thinking until the seventeenth century.

Galen discussed the pineal gland in the eighth book of his anatomical work On the usefulness of the parts of the body. He explained that it owes its name (Greek: kônarion, Latin: glandula pinealis) to its resemblance in shape and size to the nuts found in the cones of the stone pine (Greek: kônos, Latin: pinus pinea). He called it a gland because of its appearance and said that it has the same function as all other glands of the body, namely to serve as a support for blood vessels.

In order to understand the rest of Galen’s exposition, the following two points should be kept in mind. First, his terminology was different from ours. He regarded the lateral ventricles of the brain as one paired ventricle and called it the anterior ventricle. He accordingly called the third ventricle the middle ventricle, and the fourth the posterior one. Second, he thought that these ventricles were filled with “psychic pneuma,” a fine, volatile, airy or vaporous substance which he described as “the first instrument of the soul.” (See Rocca 2003 for a detailed description of Galen’s views about the anatomy and physiology of the brain.)

Galen went to great lengths to refute a view that was apparently circulating in his time (but whose originators or protagonists he did not mention) according to which the pineal gland regulates the flow of psychic pneuma in the canal between the middle and posterior ventricles of the brain, just as the pylorus regulates the passage of food from the esophagus to the stomach. Galen rejected this view because, first, the pineal gland is attached to the outside of the brain and, second, it cannot move on its own. He argued that the “worm-like appendage” [epiphysis or apophysis] of the cerebellum (nowadays known as the vermis superior cerebelli) is much better qualified to play this role (Kühn 1822, pp. 674-683; May 1968, vol. 1, pp. 418-423).

1.2 Late Antiquity

Although Galen was the supreme medical authority until the seventeenth century, his views were often extended or modified. An early example of this phenomenon is the addition of a ventricular localization theory of psychological faculties to Galen’s account of the brain. The first theory of this type that we know of was presented by Posidonius of Byzantium (end of the fourth century AD), who said that imagination is due to the forepart of the brain, reason to the middle ventricle, and memory to the hind part of the brain (Aetius 1534, 1549, book 6, ch. 2). A few decades later, Nemesius of Emesa (ca. 400 AD) was more specific and maintained that the anterior ventricle is the organ of imagination, the middle ventricle the organ of reason, and the posterior ventricle the organ of memory (Nemesius 1802, chs. 6-13). The latter theory was almost universally adopted until the middle of the sixteenth century, although there were numerous variants. The most important variant was due to Avicenna (980-1037 AD), who devised it by projecting the psychological distinctions found in Aristotle’s On the soul onto the ventricular system of the brain (Rahman 1952).

1.3 Middle Ages

In a treatise called On the difference between spirit and soul, Qusta ibn Luqa (864-923) combined Nemesius’ ventricular localization doctrine with Galen’s account of a worm-like part of the brain that controls the flow of animal spirit between the middle and posterior ventricles. He wrote that people who want to remember look upwards because this raises the worm-like particle, opens the passage, and enables the retrieval of memories from the posterior ventricle. People who want to think, on the other hand, look down because this lowers the particle, closes the passage, and protects the spirit in the middle ventricle from being disturbed by memories stored in the posterior ventricle (Constantinus Africanus 1536, p. 310). Qusta’s treatise was very influential in thirteenth-century scholastic Europe (Wilcox 1985).

In several later medieval texts, the term pinea was applied to the worm-like obstacle, so that the view that the pineal gland regulates the flow of spirits (the theory that Galen had rejected) made a come-back (Vincent de Beauvais 1494, fol. 342v; Vincent de Beauvais 1624, col. 1925; Ysaac 1515, part 2, fol. 172v and fol. 210r; Publicius 1482, ch. Ingenio conferentia). The authors in question seemed ignorant of the distinction that Galen had made between the pineal gland and the worm-like appendage. To add to the confusion, Mondino dei Luzzi (1306) described the choroid plexus in the lateral ventricles as a worm which can open and close the passage between the anterior and middle ventricles, with the result that, in the late Middle Ages, the term ‘worm’ could refer to no less than three different parts of the brain: the vermis of the cerebellum, the pineal body and the choroid plexus.

1.4 Renaissance

In the beginning of the sixteenth century, anatomy made great progress and at least two developments took place that are important from our point of view. First, Niccolò Massa (1536, ch. 38) discovered that the ventricles are not filled with some airy or vaporous spirit but with fluid (the liquor cerebro-spinalis). Second, Andreas Vesalius (1543, book 7) rejected all ventricular localization theories and all theories according to which the choroid plexus, pineal gland or vermis of the cerebellum can regulate the flow of spirits in the ventricles of the brain.
~Lokhorst, Gert-Jan, “Descartes and the Pineal Gland”, The Stanford Encyclopedia of Philosophy (Fall 2008 Edition), Edward N. Zalta (ed.).

René Descartes (1596-1650) was a French philosopher, mathematician, scientist, and writer.  He has been called the “Father of Modern Philosophy”.  He wrote;

“Since it is the only solid part in the whole brain which is single, it must necessarily be the seat of the common sense, i.e., of thought, and consequently of the soul; for one cannot be separated from the other.”

I’m glad he was wrong because I’d hate to think since I’m now without a pineal gland that I have no soul. 😉 Still, his work in ‘Treatise of Man’ and ‘Passions of the Soul’ is very interesting reading.

By the end of the nineteenth century, several scientists introduced the hypothesis that the pineal gland is a phylogenic relic, a vestige of a dorsal third eye. A modified form of this theory is still accepted today. Also, scientists began to theorize that the pineal gland is an endocrine organ. This was proven in the twentieth century. The hormone secreted by the pineal gland, melatonin, was first isolated in 1958. Melatonin is secreted in a circadian rhythm, which is interesting in view of the hypothesis that the pineal gland is a vestigial third eye. Madame Blavatsky, the founder of theosophy, identified the “third eye” discovered by the comparative anatomists of her time with the “eye of Shiva” of “the Hindu mystics” and concluded that the pineal body of modern man is an atrophied vestige of this “organ of spiritual vision”. The pineal gland is occasionally associated with the sixth chakra (also called Ajna or the third eye chakra in yoga). It is believed by some to be a dormant organ that can be awakened to enable “telepathic” communication.

Today we know that the pineal gland It is sensitive to different levels of light and is essential to the functioning of an animal’s biological clock. In many animals, including humans, it synthesizes a hormone called melatonin in periods of darkness. Melatonin synthesis is halted when light hits the retina of the eye, sending impulses to the gland via the optic nerve. Besides influencing daily, or circadian, rhythms such those of as sleep and temperature, the pineal gland and melatonin appear to direct annual rhythms and seasonal changes in animals.

So, I’m sometimes sad to be missing the seat of my soul, my third eye and especially my circadian rhythms, but I am happy to know I can survive without it.  As for the circadian rhythms, I do see the effect. I stay up at night, sleep whenever and don’t generally function on a 24 hour day. I tend towards 30-36 hour days way too often and about 5 hours worth of sleep. I sometimes wonder if I’ve lost some precious potential to reach a higher degree of spirituality for my lack of a pineal gland but then I believe that resides elsewhere, where my soul resides also.

There’s much more at the cited link. It’s the most comprehensive information I’ve been able to find about Pineal glands and so very interesting how our knowledge has progressed.

Edited to add links to my previous posts about Pineal Gland Brain tumors.

Pineal Gland Tumor

What is a Pineal Gland Tumor?

“Ordinary riches can be stolen, real riches cannot. In your soul are infinitely precious things that cannot be taken from you.” ~Oscar Wilde