History of the pineal gland
The history of the pineal gland is an account of the scientific development on the understanding of the pineal gland from the ancient Greeks that led to the discovery of its neuroendocrine properties in the 20th century CE. As an elusive and unique part of the brain, the pineal gland has the longest history among the body organs as a structure of unknown function – it took almost two millennia to discover its biological roles. Until the 20th century, it was recognised with a mixture of mysticism and scientific conjectures as to its possible nature.
Source: Wikipedia — History of the pineal gland (CC BY-SA 4.0)