My studies on the physiology of colours together with Francis Ford Coppola in "Un sogno lungo un giorno" allowed me to understand which is the physical reaction we have in front of colours. When we say "colour", we refer to the visible part of light, energy that vibrates at a certain weave length. If energy, just like light, reaches an object or not, depends on how it is positioned, filtered or on how it express itself. We don’t see light through our eyes only but through our body as a whole: we are like sensitive screens on which lights weaves impress a reaction which modifies our body, our metabolism and our blood pressure. As a scientifically proved consequence, our state of mind changes in relation to a certain image or a particular light or colour.
In the "The Last Emperor" we tried to show how it is possible to relive our existence through a symbiosis between life’s phases and colours, and to understand how we may visually represent the phases of our life through colours. Red could represent the life-giving blood; orange may be related to our five-year old age, to the warmth of our mother, family and home; yellow may be identified with our twelve-year old age, our adolescence, the discovery of sexuality and self-consciousness. Green may represent our twenty-year old age, the time for knowledge, for learning: the Young Emperor is in his twenties when he succeeds in discovering what exist outside the forbidden city. He used to call this outside space the city of sounds, as he could only listen to its sounds without seeing it from its confined living space. Blue represents the period between thirty and fifty years of age, and represents the climax of our intelligence of our concentration skills, our consciousness of freedom. Then we reach our maturity at sixty years of age, through the indigo colour, which represents our sense of power and a certain materiality.  Indigo is followed by violet, which reveals the natural need of looking back at our past and reliving through the new generations, transmitting all our knowledge to the young who would take it on. This is in essence the meaning of the movie ”The last Emperor“.
I believe that this second phase of my life offers me the chance to discover these emotions.
In the movie "La luna" directed by Bernardo Bertolucci, I dealt with colours as symbols, with our own individual vision of colours. Since we were in our mother’s womb, every single event in our life influenced our psychology and surely colours related to those events have left their mark on us in a peculiar way. As Plato says, we see through our own personality’s contact with an image, so all events in our life that made us grow can be translated into this type of vision, finding conflict or harmony in certain colours.
When we look at a painting, a play, a movie or a television programme, we observe a group of images with a certain tone of light, shadow and colours, conflicting or harmonious, which convey specific emotions. 
This physical reaction was surely known to the architects who designed the city of Las Vegas. They succeeded in stimulating human blood pressure through millions of lights and warm shades mixed together in order to continuously inject energy into people, so that the natural need for rest and relax does not appear even at sun set. It is therefore possible to create a solar artificial light that excites and cause people to continue gambling.
This is what I expressed in the movie "Un sogno lungo un giorno".
Before going into writing with light, I should briefly make a preliminary introduction to the topic.
By attending, either as a student or as a professor, many lecturers on cinema around the world, I noticed that education to cinema is focused on technological issues, and little attention is dedicated to the real meaning of things and the strong relationship between cinema and other forms of art.
Therefore I felt that filling this gap was a necessity and, during the past thirty years, I have studied and researched the philosophy of vision to better understand the origins cinema, in the first place photography and painting, to better understand the history of art and how Visual Arts in general have developed, in order to obtain more information on architecture, sculpture, music and psychoanalysis. Everyone who works in Visual Arts and cinema interacts with those fields, maybe in an unconscious way. In the Renaissance this interaction was more conscious because, in order to understand the real meaning of the things, Eastern and Greek philosophy were studied and researched: this approach has been lost over the centuries.
Thanks to my research I gathered trough the years publications, opinions, formulas, poems, images and paintings and I started a progressive analysis on their use in the movies I was working at. It has been a continuous research that helped me to express myself in every movie I have done and, by continuing to do so, I have realised that the collecting and organising activity over these materials has been following the evolution of my life and experiences.
So, since I started to work as an art director in 1968 at the movie "Giovinezza, giovinezza" my first black and white movie, during the first ten years of my artistic evolution I focused on the relationship between light and shadow and I entirely based my work on this relationship until I started to work on "Apocalypse now".  
At that stage, I felt the need to better understand the real structure of this element, this essence and visible energy I was constantly handling during my work on movies: light.  I spent one year in a house studying old and new issues, and I finally discovered the world of colours.
Thereafter, I continued my artistic life following this new hint of knowledge.