_Mrs. B._ Because a body always appears to be of the colour which it reflects; for, as we see only by reflected rays, it can appear of the colour of those rays, only. _Caroline._ But we see all bodies of their own natural colour, Mrs. B.; the grass and trees, green; the sky, blue; the flowers of various hues. _Mrs. B._ True; but why is the grass green?--because it absorbs all, except the green rays; it is, therefore, these only which the grass and trees reflect to our eyes, and this makes them appear green. The flowers, in the same manner, reflect the various colours of which they appear to us; the rose, the red rays; the violet, the blue; the jonquil, the yellow, &c. _Caroline._ But these are the permanent colours of the grass and flowers, whether the sun's rays shine on them or not. _Mrs. B._ Whenever you see those colours, the flowers must be illumined by some light; and light, from whatever source it proceeds, is of the same nature; composed of the various coloured rays which paint the grass, the flowers, and every coloured object in nature. _Caroline._ But, Mrs. B., the grass is green, and the flowers are coloured, whether in the dark, or exposed to the light? _Mrs. B._ Why should you think so? _Caroline._ It cannot be otherwise. _Mrs. B._ A most philosophical reason indeed! But, as I never saw them in the dark, you will allow me to dissent from your opinion. _Caroline._ What colour do you suppose them to be, then, in the dark? _Mrs. B._ None at all; or black, which is the same thing. You can never see objects, without light. White light is compounded of rays, from which all the colours in nature are produced; there, therefore, can be no colour without light; and though a substance is black, or without colour, in the dark, it may become coloured, as soon as it becomes visible. It is visible, indeed, only by the coloured rays which it reflects; therefore, we can see it only when coloured. _Caroline._ All you say seems very true, and I know not what to object to it; yet it appears at the same time incredible! What, Mrs. B., are we all as black as negroes in the dark? you make me shudder at the thought. _Mrs. B._ Your vanity need not be alarmed at the idea, as you are certain of never being seen, in that state. _Caroline._ That is some consolation, undoubtedly; but what a melancholy reflection it is, that all nature which appears so beautifully diversified with colours, is really one uniform mass of blackness! _Mrs. B._ Is nature less pleasing for being coloured, as well as illumined, by the rays of light? and are colours less beautiful, for being accidental, rather than essential properties of bodies?