Letter to Michel Pastoureau

In most French bookstores, the books of Michel Pastoureau take most of the shelf dedicated to colors. The publication of the book “Color Never Comes Alone” was the opportunity for the French professor to give a lecture at the Villa Medicis; it inspired me this letter.

Michel Pastoureau’s conference was about black and white, here illustrated by the Yin and Yang symbol (source Wiki commons)

Keywords: Multidisciplinary aspects – vocabulary – color order

Dear Professor Pastoureau,

Thank you very much for having shown us some facets of these two colors, black and white, and thus the multidisciplinary side of the world of color; thank you also for having warned us against all these unsavory books that deal with the symbolism of color, I will look at them with a critical spirit when they fall into my hands.

It is the same critical spirit that leads me to discuss what you say about Newton, which, on the one hand, would have excluded black and white from colors and, on the other hand, would have imposed a new order of colors.

Let us not confuse what Newton said with what his contemporaries or post-contemporaries understood.

Newton’s treatise on optics and his color circle

Newton did not impose an order on colors, he only proposed an order in the “spectral” colors, the colors of the rainbow; their “natural” order is the one in which they appear in this optical phenomenon.

Today, everyone agrees that “color” can be described by three parameters, and therefore could be represented as a point in a three-dimensional finite space.

Starting the reading of your book “Color Never Comes Alone”, I realize that I am one of those people who annoy you by calling color what you call “nuance”.

When we talk about color, we should first agree on the vocabulary, quoting terms that other people use to say the same thing, the important point being to know “what we are talking about”. Even if what we call color is for you a “shade”, your “colors” can also be represented as such a point in this space, they would be seen as “representatives” of the cloud of shades that surrounds it.

But already in a two-dimensional space there is no possible order.

Colors and Oder

Imagine, for example, that every person in this conference room is a color, and that they have visually similar colors in their vicinity. How would you give each one an order number so that the colors that are most similar are the ones before and after them? You can’t do that!

A representation view of the conference room; you are the black dot near the desk. Each person is represented by a circle; on the right, let us assume that each person has a color, with all neighbors having a close color.

For example, you may try by ordering them assigning a number to each color-person, starting with the first row from left to right, the next row from right to left, and so on, forming a long ribbon. But then, the person just behind me in the next row would have a much larger number than the person in the same row, which is much further away.

Two different orders of colors; at the bottom, colors forming a ribbon. On the left colors are ordered according to rows, on the right, according to diagonals

Whatever the method, it will not be possible to represent a satisfactory order. Nevertheless, one could consider the people along the wall only (those who have not found a seat) and order them, just following the perimeter of the conference room.

The conference room, with the people standing near the walls also represented by colors; these colors can be ordered in a satisfying way, just following the perimeter of the room.

This is exactly what Newton does with his color circle: the spectral colors form a boundary in the color space and can therefore be ordered.

The order of spectral and extra-spectral colors

In fact, to be more precise, spectral colors form most of the circumference, not all; it is “closed” by non-spectral colors; in the analogy with this conference room, the non-spectral colors would be represented by people against the wall who would see you from behind. The other color-person along the wall could be assigned a wavelength from the visible spectrum: if each of them radiated in turn, he/she would produce a certain color sensation.

On the left image, a few standing people are behind the lecturer; they are associated with “extra-spectral hues”. Each standing person is thus associated with a color of Newton’s color circle (displayed on the right – adapted from Handprint.com)

However, this same color sensation could be produced by different types of radiation. For example, the person who radiates red and the person who radiates green will together produce a radiation that you would not be able to distinguish from the person who radiates yellow. Radiations that, when combined, give the same colored impression are called metameric.

Some colors, including magenta, cannot be produced by radiation of a single wavelength, it is a non-spectral color (represented by a person who would see you from behind); it is obtained by combining radiation from the beginning and end of the visible spectrum.

The reddish part of a daylight spectrum is added to the blue part of another spectrum to generate magenta. (V. Lacroix CC-BY-SA 2.5)

Therefore – contrary to what you have said – it cannot be said that the physicist describes a color by its wavelength; it is not that the wavelength is not “convenient” to describe a color, it is simply not suitable.

Physics and perception

Indeed, physics is not enough to describe/understand color; color is a production of the mind before it is an abstraction. In order for there to be a colored sensation, a light ray must penetrate the retina, which, after passing through the crystalline lens, will be captured by photo-sensitive cells and transformed into a nervous signal, then interpreted as a colored sensation.

Physics and chemistry only deal with what happens before reaching the retina; biology, neurology and psychology deal with what happens afterwards.

This sensory point of view, which brings together several sciences, allows us to understand color, but is not enough to approach its complexity.

Artistic, cultural, historical, symbolic and even technological points of view are necessary to explore all its contours, and you have proposed a certain number of them to us. Each color specialist will give more importance to one or the other aspect according to his or her affinities and training.

Color is inherently multi-disciplinary and some statements may only be valid in a certain context; would the unsavory books you quote become acceptable? I don’t know, but I do know that there are a lot of books on color that are misconceived, not just books about the symbolism of color.

Leave a Reply

Your email address will not be published. Required fields are marked *