The pineal gland has a hormonal and mystical component, described since time immemorial; its main secretion product with recognized health effects is melatonin, which is involved in the light/dark phenomenon. Additionally, this gland has been related to spiritual aspects and divine connection; in fact, for certain traditions, they define it as the “Third Eye” and establish it as the link between the “Body and Mind”. This review describes the most relevant aspects of the functioning of the pineal gland (from a hormonal point of view) and its possible role from a mystical-spiritual point of view.