So my previous post on this topic spun out some theories based on very little at all. I didn’t actually believe that Tolkien himself had any views on the issue. It was only afterwards, and with the addition of more coffee, that I realised the issue is right there in the text of The Fellowship of the Ring:
“For I am Saruman the Wise, Saruman Ring-maker, Saruman of Many Colours!’https://www.goodreads.com/quotes/101991-for-i-am-saruman-the-wise-saruman-ring-maker-saruman-of
I looked then and saw that his robes, which had seemed white, were not so, but were woven of all colours, and if he moved they shimmered and changed hue so that the eye was bewildered.
I liked white better,’ I said.
White!’ he sneered. ‘It serves as a beginning. White cloth may be dyed. The white page can be overwritten; and the white light can be broken.’
In which case it is no longer white,’ said I. ‘And he that breaks a thing to find out what it is has left the path of wisdom.’
White light can be broken is an overt reference to Isaac Newton’s theory of light and I’m confident that is a deliberate and intentional reference. A man of Tolkien’s background, nationality and intellectual interests would absolutely be aware of Newton’s famous experiments with light. Newton was a key figure in British historical propaganda of the qualities of the British and while Tolkien may have had some scepticism about that as an Oxford man is obliged to be sceptical about the achievements of Cambridge.
There are shades in Gandalf’s reply of John Keats’s remarks on Newton that he had ‘destroyed all the poetry of the rainbow, by reducing it to the prismatic colours.’
Prior to Newton, there were multiple theories of colour* but a classical theory ascribed to Aristotle was that colour was derived from balances of light and darkness. Gandalf (at this point) is famously grey but later comes back as Gandalf the White – and distinctly white, not white-is-actually-just-a-big-mix-of-colours.
I don’t want to over-egg the colour symbols of the wizards. We only learn of three (white, grey, brown) which more suggest Catholic monk robe colours than any grand symbolic scheme. However, this one scene does contrast Saruman and Gandalf as two different schemes for mixing underlying colours and Saruman is overtly a more MODERN one.
Newton’s theory was also expressly ATOMIC or rather “corpuscular”. The idea was that tiny light particles make up visible light and travel with different properties. When refracted the tiny particles follow different angles and hence can be separated out. The theory is also incorrect and could not explain properties of light such as diffraction and polarisation. Resolving these aspects of light would require quantum mechanical theories of light and the idea of wave-particle duality.
I don’t think it is unreasonable to see Saruman as a symbol of toxic modernism in his use of colour given all the other ways Tolkien uses Saruman as representing industrial ugliness. By extension, Gandalf stands for the opposite and in this case they also stand for two different conceptions of nature: Gandalf in the top-down abstract principles/essences/categories shape the kind of thing a person/object/thing is versus Saruman representing the corpuscular/atomic counterpoint that is the arrangement/combination of more basic non-descript building blocks that emerged as different things.
That gives me a different answer to the question of whether Gandalf knows about atoms: he does know about atoms and he is very much against them as an idea.
*[and there still are multiple theories because colour crosses physics and perception]