Psychoactive plants have been consumed by many cultures, cults and groups during religious rituals and ceremonies for centuries and they have been influential on the eruption of many images, secret and religious symbols, esoteric geometrical shapes, archetypes, religious figures, and philosophy of religions since the dawn of Homo sapiens. Some of the psychoactive plants used for religious purposes were: narcotic analgesics (opium), THC (cannabis), psilocybin (magic mushrooms), mescaline (peyote), ibogaine (Tabernanthe iboga), DMT (Ayahuasca and Phalaris species), Peganum harmala, bufotenin, muscimol (Amanita muscaria), Thujone (absinthe, Arthemisia absinthium), ephedra, mandragora, star lotus, Salvia divinorum etc. An important property of these natural chemicals is to induce the human psyche to perceive optical forms and shapes that are existent in the subconscious and presumed collective unconsciousness, and which emerge during certain trance states and ASCs (altered states of consciousness). Some of these simple geometric forms are called entoptic images and phosphenes. Entopic images and phosphenes have been found in various cultural works of art and in the drawings on cave walls, which were formed during shamanic religious rituals since Neolithic times. Also entoptic images exist in many folkloric, traditional and cultural geometrical shapes. Long before the creation of languages, visual perception and information were the only source for mankind, alone of the primates, to perceive the outer world. This article reviews the possibility of an ancient forgotten language of visual signs and symbols, which is genetically existent in the human brain and emerges during ASCs, trance states, and consciousness altered by psychoactive plants.