White light

“ The light of the sun is made up of seven colours, though God has so perfectly blended them that we see only white light; but all these colours may be traced in the seven-coloured arch, which is a token to men of His mercy, and a sign that while the earth remains "seed-time and harvest, cold and heat, summer and winter, day and night, shall not cease."
The smallest portion of light which we can speak of is called a ray of light. ”

“ It is a sad thing to think of, that when we put the candle out, and step into bed, we become blacker than the blackest negro that was ever emancipated. But without light there can be no colour, for there is no material, so to speak, from which to manufacture it. White light, as we have said before, is made up of red, blue, and yellow, and it is by the absorption of one or all of these that all tints are formed. ”

“ If we set the amount of light reflected by white paper as 100, then a surface painted with "emerald-green" reflects about eight parts of white light; artificial ultramarine, two or three parts; red lead, seven or eight, etc. Some white light is always present; its general effect is to soften the color and reduce its action on the eye; when the proportion of white is very large, only a faint reminiscence of the original hue remains; we say the tint is greenish-gray ”

“ As the white light of the sun passes through the raindrops, the violet part of the light is bent more than any of the rest, the indigo part is bent not quite so much, and so on to the red, which is bent least of all. So all the colors fan out from the single beam of white light and form a band of color, which we call the rainbow. ”

“ Had every ray of light been a pure white, and incapable of being separated into any other colours, the scene of the universe would have exhibited a very different aspect from what we now behold. One uniform hue would have appeared over the whole face of nature, and one object could scarcely have been distinguished from another. The different shades of verdure which now diversify every landscape, the brilliant colouring of the flowery fields, and almost all the beauties and sublimities which adorn this lower creation would have been withdrawn. ”

“ Nothing so nearly approaches pure white as the palest blue; nothing is so nearly black as the darkest.
Green has been assigned by nature the place of the universal background. It is the complementary colour of red, softening and assimilating it by reflected shadows, and setting off the glory of every flower and fruit. The expression of green is gaiety and modesty, light and tenderness, shadow and repose, to both the eye and the mind. ”

“ Not only may white light be resolved by a prism into a number of brilliant colours, but, by an appropriate arrangement, these colours can be re-combined into white light: the visual sensation which seems perfectly simple proves to be highly compound. ”

“ Anything which, when illuminated by a source of white light, reflects all its various components equally and without absorbing a larger proportion of some than of others, appears white or grey. Between white and grey there is no essential difference except in luminosity, or brightness, that is to say, in the quantity of light reflected to the eye, or—to go a step further back—in the amplitude of the ether waves. Under different conditions of illumination any substance which reflects all the rays of the spectrum equally may appear either white or grey, or even black. ”

“ White with the worship of ages, ineffably beautiful and pathetic, is the old light-religion of humanity—a sublime nature-mysticism in which Light was love and life, and Darkness evil and death. For the early man light was the mother of beauty, the unveiler of color, the elusive and radiant mystery of the world, and his speech about it was reverent and grateful. ”

“ Two unique tints struck our view; blue and white—the blue as vivid as turquoises, sapphires, or cobalt, in fact the very deepest azure that can be imagined, and the white as pure as silver, snow, milk, marble, or the finest crystallized sugar! The blue was the sky repeated by the sea; the white was the town. It is impossible to conceive anything more radiant and more dazzling—to imagine light more diffused, and, at the same time, more intense. ”

“ In the flame which goes up are two lights: one light is a bright white and one light is united with a dark or blue; the white light is that which is above and ascends in a straight path, and that below is that dark or blue light, and this light below is the throne to the white light and that white light rests upon it, and they unite one to the other so that they are one. And this dark light, or blue colour, which is below, is the precious throne to the white. And this is the mystery of the blue. ”

“ I remember one of my old teachers calling the attention of our class to the fact, and demonstrating it, that a ray of white light was not so simple a thing as we might think it to be. When you see a white ray of sunlight streaming through some window or other aperture into a dark room, you might think that the bar of white light consists simply of one white ray. ”

“ And from the height of this perception all that had previously tormented and preoccupied him suddenly became illumined by a cold white light without shadows, without perspective, without distinction of outline. All life appeared to him like magic-lantern pictures at which he had long been gazing by artificial light through a glass. Now he suddenly saw those badly daubed pictures in clear daylight and without a glass. ”

“ On the most likely hypothesis as to the physical nature of light, colour depends on the rate of vibration of the luminiferous aether, and white light is a compound of all the colours in definite proportion. When a surface reflects solar light into the eye without affecting this proportion, it is white, but if it absorbs all the light so as to reflect nothing, it appears to be black. ”

“ Finally, by means of a rotating disk, on which are spread in sectors the colours of the spectrum, we blend together the prismatic colours in the eye itself, and thus produce the impression of whiteness.
Having unravelled the interwoven constituents of white light, we have next to inquire, What part the constitution so revealed enables this agent to play in Nature? To it we owe all the phenomena of colour, and yet not to it alone; for there must be a certain relationship between the ultimate particles of natural bodies and white light, to enable them to extract from it the luxury of colour. ”

“ White is our only semblance to light, and what a leaden symbol it is when we regard the brightness of our example!
Black is our deepest dark, and how shallow it is when we try to look into the depth of the shadows about us! ”

“ It will help us to realize the nature of the defect to assume, which is not quite the case, that white light is composed of red, green, and violet in equal proportions and of equal luminosity; then to eyes which are incapable of seeing one of the colors, one third of the illumination of natural objects is extinguished, and the appearance the objects present is not that of their real color, but only of that fraction of their real color in which the two visible colors are combined in them. ”

“ It throws a single ray, separated from the rest,—red, yellow, blue, or any intermediate shade,—upon an object; never white light; that is the province of wisdom. We get beautiful effects from wit,—all the prismatic colors,—but never the object as it is in fair daylight. ”

“ If light is color, why should it seem white in one case and some other hue in another? It is because in the whiteness of light are contained all the colors of which we are conscious. Very likely you know the experiment by which the truth of this is shown. Supposing you are still in the cellar and place in the pathway of the shaft of light a prism—that is to say, a bar of glass not round or square, but triangular—what will happen? The glass being transparent, the light will pass through it. ”

“ When the light falls on a rounded object there is nearly always one place upon it where the light strikes, creating a white light—no matter what the color of the object—which artists call the high light. ”

“ It is known that white light consists of the admixture of coloured rays in certain proportions, and that the beautiful prismatic colours seen in the rainbow are produced by the different degree in which the various rays of colour are bent when passing from one transparent substance into another of different density. ”

“ It is not true that white light necessarily contains rays of all possible wave-lengths: the sensation of whiteness may, as will be shown by and bye, be produced quite as effectively by the combination of only two or three different wave-lengths. Nor is it true that such colours as we see in nature are always due to light of a single wave-length ”

“ That natural colours are the result of white light, and not innate properties of the bodies themselves, is most conclusively shown by placing coloured bodies in monochromatic light of another kind, when they will appear either of the colour of that light, or, by absorbing it, become black; whereas, when placed in light of their own character, the intensity of colour is greatly increasing. ”

“ The result is, that instead of a spot of white light we have a narrow band of brilliant colours which succeed each other in regular order, from violet at one end through blue, green, and yellow to red at the other. ”

“ It is noticeable, however, that the white light resulting from the combination of blue and yellow, though it cannot be distinguished by the eye from ordinary white light, is yet possessed of very different properties. Most coloured objects when illuminated by it have their hues greatly altered; a piece of ribbon, for example, which in common light is bright red, will appear when held in the blue-yellow light to be of a dark slate colour, almost black. ”

“ This apparatus shows then that ordinary white light may be regarded as a mixture of all the variously coloured lights which occur in the spectrum, the sensation produced when it falls upon the eye being consequently a compound one.
From these and similar experiments the scientific neophyte is not unlikely to draw an erroneous conclusion. White light, he is apt to think, is always due to the combined action of rays of every possible wave-length, while coloured light consists of rays of one definite wave-length only. ”

“ The several Rays therefore in that white Light do retain their colorific Qualities, by which those of any sort, whenever [Pg 147] they become more copious than the rest, do by their Excess and Predominance cause their proper Colour to appear.
And by the same way of arguing, applied to the third Experiment of this second Part of the first Book, it may be concluded, that the white Colour of all refracted Light at its very first Emergence, where it appears as white as before its Incidence, is compounded of various Colours. ”

“ This also explains the circumstance that a landscape, illuminated by bright white clouds, appears more yellow in general hue than when the clouds are not bright, though still retain-in their whiteness, the strong white light stimulating more powerfully the sets of nerves concerned in the production of yellow. ”

“ The answer is, that a quantity of white light not decomposed, and a part of all the colour rays, reach all parts of the spectrum, however carefully it is sheltered, but that so many more red rays get to the top, so many more of the yellow to the middle, and so many more blue to where that colour appears most brilliant, that these are seen nearly pure, whilst where the red and yellow or yellow and blue mix they produce distinct kinds of colour, and where the blue at the bottom is faint, and some of those red rays fall that do not reach the red part of the spectrum, the violet is produced. ”

“ I cannot see that the sun may be white, and that each color gives a share of its own virtue to it, and that their accord determines it. There is no color without an extrinsic support; from which we learn that it is itself an exterior thing, the diverse witness that matter renders to the pure source of indivisible splendor. Do not pretend to separate light; since it is light which divides darkness, producing seven notes according to the intensity of its effort. ”

“ Greens and blues, purples and whites, melt into one another, fade, and come again, and change with the changing sun. Sometimes they are as richly diaphanous as a precious stone, and glow from within with a deep, inexplicable light. Sometimes the white intricacies of dropping foam become opaque and creamy. And always there are the rainbows. If you come suddenly upon the Falls from above, a great double rainbow, very vivid, spanning the extent of spray from top to bottom, is the first thing you see. ”

“ It is precisely because the hue called white is the one which is associated with the light of our sun that we regard whiteness as synonymous with absence of colour. We take sunlight as our standard of neutrality, and anything that reflects it without altering the proportions of its constituents we consider as being colourless. ”

“ Green and purple, again, are complementaries. All{42} the spectral colors added together also make white light, such as we daily experience in the sunshine. Furthermore, both homogeneous ether-waves and heterogeneous ones may make us feel the same color, when they fall on our retina. Thus yellow, which is a simple spectral color, is also felt when green light is added to red; blue is felt when violet and green lights are mixed. Purple, which is not a spectral color at all, results when the waves either of red and of violet or those of blue and of orange are superposed. [15]
Fig. ”

“ Thus white light is a compound thing containing long waves with which heat phenomena are associated, waves of medium length to which alone the eye is tuned, and short waves which have a decided action on some metallic salts which are unaffected by the others. ”