The reason I start this thread is due to my own experience with this strange altered state of consciousness

Synesthesia

How someone with synesthesia might perceive certain letters and numbers.

Synesthesia (also spelled synæsthesia or synaesthesia, plural synesthesiae or synaesthesiae)—from the Ancient Greek σύν (syn), "together," and αἴσθησις (aisthēsis), "sensation"—

is a neurologically-based condition in which stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway.[1][2][3][4] People who report such experiences are known as synesthetes.

In one common form of synesthesia, known as grapheme → color synesthesia or color-graphemic synesthesia, letters or numbers are perceived as inherently colored,[5][6] while in ordinal linguistic personification, numbers, days of the week and months of the year evoke personalities.[7][8]

In spatial-sequence, or number form synesthesia, numbers, months of the year, and/or days of the week elicit precise locations in space (for example, 1980 may be "farther away" than 1990), or may have a (three-dimensional) view of a year as a map (clockwise or counterclockwise).[9][10][11]

Yet another recently identified type, visual motion → sound synesthesia, involves hearing sounds in response to visual motion and flicker.[12] Over 60 types of synesthesia have been reported by people,[13] but only a fraction have been evaluated by scientific research.[14] Even within one type, synesthetic perceptions vary in intensity [15] and people vary in awareness of their synesthetic perceptions.[16]

While cross-sensory metaphors (e.g., "loud shirt," "bitter wind" or "prickly laugh") are sometimes described as "synesthetic," true neurological synesthesia is involuntary.

It is estimated that synesthesia could possibly be as prevalent as 1 in 23 persons across its range of variants.[17] Synesthesia runs strongly in families, but the precise mode of inheritance has yet to be ascertained.

Synesthesia is also sometimes reported by individuals under the influence of psychedelic drugs, after a stroke, during a temporal lobe epilepsy seizure, or as a result of blindness or deafness. Synesthesia that arises from such non-genetic events is referred to as "adventitious synesthesia" to distinguish it from the more common congenital forms of synesthesia.

Adventitious synesthesia involving drugs or stroke (but not blindness or deafness) apparently only involves sensory linkings such as sound → vision or touch → hearing; there are few, if any, reported cases involving culture-based, learned sets such as graphemes, lexemes, days of the week, or months

Alan