From Oliver Wendell Holmes, "The Human Body and Its Management," reprinted in Pages from an Old Volume of Life:

"The dark side of a street is far more subject to disease than the light side. Sir James Wylie found three times as many cases of disease on the shaded side of the barracks at St. Petersburg as on the other side. Dupuytren is said to have wrought a cure in the case of a lady in a seemingly desperate condition, by simply removing her from her dark quarters to a brighter residence, and keeping her as much as possible in the daylight. There is no better testimony on any such point than that of Miss Florence Nightingale. What she says of the value of light to those who are ill indicates no less its necessity for those who are well:--

"Second only to fresh air, however, I should be inclined to rank light in importance for the sick. Direct sunlight, not only daylight, is necessary for speedy recovery....Instances could be given almost endless, where in dark wards, or in wards with a northern aspect, even when thoroughly warmed, or in wards with borrowed light, even when thoroughly ventilated, the sick could not by any means be made speedily to recover.

"Very few persons seem to have a due sense of the luxury and benefit of aprication, or immersion in the sunshine bath, which every fair day will furnish gratuitously to all applicants....The passion of the sunflower for "her god" is famous in song. But there are examples of still more ardent devotion than hers. Mr. Jesse tells how a potato, left in a dark cellar with only one opening, sent its shoot twenty feet to get at the light through that little crevice....There is a little streak of morning sun which in early spring comes in between two buildings near by me and traverses the open space beyond, as the sun moves up the heavens. The sensible barn-yard fowls of the Infirmary hen-coops follow it as it slowly travels along, as faithfully as if their brains were furnished with heliostats.

"It is well to remember that there is something more than warmth in sunlight. The skin does not tan and freckle in warm, dark rooms. Photography reminds us that there is a chemistry in sunshine, without which that beautiful art would be unknown....

"The tailor's art has blanched the surface of our bodies to the whiteness of celery. Like that, we are buried alive, all but our heads. We can hardly doubt that the condition of the primitive man was to bask in unimpeded sunshine, and that in depriving himself of it to so great an extent he must pay the price in the form of some physical deterioration. Men and women must have sunshine ripen them as much as apples and peaches...."