Sometimes, husbands and wives can find communication difficult, particularly when one of the pair does not assess correctly the tenor of the spouse's mood.
Mrs Olga Chekhov is a case in point. On one occasion, seeking with commendable ambition to rise to the intellectual stature of her husband, and thinking, I suppose, that he of all people ought to know the answer, she asked him: "What, Anton Pavlovich, can we take to be the meaning of this life?" But the playwright's answer was on quite a different level: "It is like asking what a carrot is. A carrot is a carrot, and nothing more is known."
You, too, might say the same if your spouse were to ask you why a glass of milk is white. And yet, unlike anything pertaining to the meaning of our earthly lives, there is an answer.
Milk consists of a mixture of tiny globules of fat suspended in a water base, and insofar as these particles have any hue at all, it is not white: milk, in fact, should not be white at all, but relatively colourless - but it takes its colour from the action of sunlight on the mixture.
Light is a sequence of electromagnetic waves to which our eyes are sensitive. It acquires its colour from its wavelength: blue light has a very short wavelength, "red waves" are relatively long, and the other colours of the spectrum fall somewhere in between. The light emanating from the sun is a mixture of them all: we call it "white".
As light waves try to make their way in a straight line through any medium, they are "scattered", or deflected from their original path, by any very small obstructions in their way, and the effectiveness of the scattering, for any particular colour, depends on size of the particles concerned.
Now the fat particles in a glass of milk are of such a size that they scatter blue light more effectively than any other: this can be seen from the bluish tinge to the film of milk adhering to an emptied glass.
But milk is "optically thick": there are so very many particles per unit volume of the liquid, that sooner or later even the "red" and other waves, after multiple encounters, are scattered to emerge from the liquid towards a waiting eye.
Moreover, the fat globules have the quality of absorbing very little of the light, so waves of every colour survive these adventures more or less unscathed.
The eye receives all the colours of the spectrum from the milk, and adds them up to the familiar colour that we know as white.