The image to the left partly illustrates the strange abnormality of the brain - which I have - called synaesthesia. I'll explain why later.
About one in twenty of us have this condition where doors in our heads (which the universal head master decrees ought to be closed) have been generously, if somewhat randomly, left open by some kindly passing subversive school caretaker.
The inner life of the synaesthesic is full of colour, texture, sound and other sensory experience which the non-synaesthesic would gawp at in non-comprehension. We are secret travellers along forgotten ways of the mind - roads invisible - and therefore inaccessible - to others. In past times we'd probably have been burnt as witches. Now we are an occasional scientific curiosity.
The most common manifestation is the perception of coloured graphemes; letters, numbers and even days of the week all have their own distinct colour. But there are other eccentricities. I remember distinctly (being about 6 years old and on a dull and routine car journey) surprising and amusing my parents by suddenly recognising - in the different shapes, colours and textures of the trees we passed - the attributes and characteristics of girls in my class at school. I think my parents assumed it was a precocious joke. But to me it was very real.
One possible explanation is that synapses which should have been 'pruned'
(Wikipedia's word) as we matured have been left in abundance, thus linking areas
of the brain which are not usually linked. Doors left open.
Hence the un-pruned tree in the image, outrageously and unashamedly orange, pink and purple - whose natural branching form is so archetypal in nature as a pattern of how organic matter often moves and behaves.