And, in his life of Pericles, he says that "green is best suited to the eye by its beauty and agreeableness, and at the same time it refreshes and strengthens the sight." From an old anonymous volume entitled "The Gentleman and Lady instructed," published in London in 1759, I extract the following: "Some authors argue for a providence, from the earth being covered with green rather than with any other color, as being such a right mixture of light and shade that it comforts and strengthens instead of weakening or grieving the eye, and they explain it in this manner: All colors that are more luminous than green overpower and dissipate the animal spirits which are employed in the sight; whereas those that are more obscure do not sufficiently exercise the animal spirits; but the rays which produce in us the idea of green fall upon the eye in such a due proportion that they give the animal spirits their proper play, and, by keeping up the struggle in a just balance, excite a very pleasing and agreeable sensation. But," says the author, "be the cause what it will, we know that its effect is certain." Richerand, the celebrated French physiologist, says, in his chapter on "Sensations": "Green is the softest of colors, the most permanently grateful; that which least fatigues the eyes, and on which they will the longest and most willingly repose. Accordingly, Nature has been profuse of green in the coloring of all plants, and she has, in some sort, dyed of this color the greater part of the surface of the globe." Dr. Thomas Dick, in his work "On the Improvement of Society by the Diffusion of Knowledge," remarks, page 206, section 6: "As the eye is constructed of the most delicate substances, and is one of the most admirable pieces of mechanism connected with our frame, so the Creator has arranged the world in such a manner as to afford it the most varied and delightful gratification. By means of the solar light, which is exactly adapted to the structure of this organ, thousands of objects of diversified beauty and sublimity are presented to the view. It opens before us the mountains, the vales, the woods, the lawns, the brooks and rivers, the fertile plains and flowery fields, adorned with every hue, the expanse of ocean, and the glories of the firmament; and, as the eye would be dazzled were a deep red color or a brilliant white to be spread over the face of Nature, the Divine Goodness has clothed the heavens with blue, and the earth with green—the two colors which are the least fatiguing and the most pleasing to the organs of sight; and, at the same time, one of these colors is diversified by a thousand delicate shades, which produce a delightful variety on the landscape of the world."
Dr. Phene, in a paper read recently by him before a scientific society in Edinburgh, advised the planting of trees in cities; among the beneficial results of which he mentions "the relief to the optic nerve through the eye resting on objects of a green color, and that, as the power of sight is strengthened and sustained by green glasses, a similar advantage would be gained by the presence of the green foliage in the