It is well known in photography that so-called artists prefer to shoot in black and white or monochrome for the simple reason that there is no colour to distract the focus of the viewer and that the focus of the subject can be brought out much better and quicker.
While we talk of black and white, there is no such a thing - there is black and white and all the shades of black and white in between. Black and white is also called monochrome to suggest that there is one colour and all the shades of it. Is that colour black or is it white? Of course, from science class we know that black is no colour and white is all colours mixed. Would monochrome then be the result of different intensity of light or whiteness? If there is different shades of whiteness, then white (which is a combination of all colours) is a truly integrated colour where there is no separation out into any of the components (primary) colours even when the whiteness is being diluted out in various shades.
It would then appear that monochrome is a truly integrated colour and that while there are shades of it, it does not discompose into its constituent colours.
In the realm of the human race, while the human race - apparently descended from a man and a woman (Daoists would generalise it into yin and yang) or from a family or from a small group of survivors of the last earthly environmental catastrophe thousands or millions of years ago - have evolved to the many shades that we now see in the faces of humanity on earth today, how then do we begin to see humanity as being the same.
I suppose that in monochrome, we would distinguish humans from non-humans. It is quite easy to say that the mountains and the rivers, the trees and the birds and the animals are non-humans - the conclusion of which unfortunately leads humans to the mindless destruction of non-human nature and the environment in the name of saving the human race.
The difficulty, even at this stage, leads us into the realm where humans are not so clever - that of ghosts and spirits and souls: are they humans or non-humans? Most mere mortals choose not to dwell on this, and it is quite clear that the only difference is the availability of a physical body - and if this is the case, then a human is being defined merely by the features of the physical body - which are most likely to be features that are most like our very own.
Hence, there is this great emotional affinity to people who look most like us or those whom we know. As features become different merely by the different sizes in relation to the rest of the body, even in monochrome, one group begin to distinguish itself from others. Layer by layer, each group finds the reasons to exclude others from their clique - so long as that group is trying to protect its environment for its own economic survival. Of course, if there are common interests to be shared or exploited, there will be an attempt to look for the commonalities from the same features that have been used to try to make distinctions before.
While we bring in colours to the pictures, while the whole picture brightens up, there will also be more distractions and more differences seen. The red begins to make itself different from the yellow and the blue, and the white tries to think it is a superior colour to the black. The common heritage of the human race or even of the living nature is easily all lost as more points of differences can be identified.
Through the eyes of a monochrome expert (Henri Cartier-Bresson or Ansel Adams), the colours are there but the black and white allow emphasis of the subject. Through the eyes of a colour expert (da Vinci, John Constable, Picasso), the colours are used to brighten up the frame but the subject still stays in focus.
In the hands of amateurs, we usually see a mixed up of the subject with the colours or lack of. There is a tendency to over-dramatise or the failure to provide a theme. In the end, we see a confused state, and everybody talking at cross-purposes.
Especially in a multi-racial society, I think is very possible to paint in monochrome and create a great theme, as well as to paint in colour to emphasis the vibrancy along the same theme.