This section is from the book "The Hygienic System: Fasting And Sun Bathing", by Herbert M. Shelton. Also available from Amazon: The Hygienic System Vol III Fasting and Sun Bathing.
The second protective mechanism developed by the body is a thickening of the corneum. This is the horny or uppermost layer of the skin. The pigment is in the skin layer that is below the sun-sensitive cells and thus gives these no protection. Thickening and hardening of the outer layer of the skin provides the needed additional protection. This is somewhat like the thickening of the same layer of the skin on the palms of the hands when we indulge in hard work.
Too much exposure to the sun occasions an excessive thickening of the corneum and, at the same time, makes the skin dry and causes it to scale. A harsh, dry, coarse skin is the result. Certainly this is not desirable and it is the worst kind of folly to stay in the sun long enough that this takes place. It is largely to avoid this dryness and harshness of the skin that olive oil and certain other lotions are employed by those who refuse to exercise a little intelligence in their sunning. Instead of buying and using the various commercial preparations that are sold to prevent the harshness and dryness of the skin that results from over-exposure, the intelligent person will avoid undue exposure and thus avoid the undesirable consequences.
A silken, smooth skin is the result of proper sunbathing. Such a result is for those who exercise intelligence in sunbathing. The ancient rule of moderation should guide us here, as in eating, exercising, etc. We have never learned self-control. We tend to go to excess in everything we do. We know next to nothing of our limitations, consequently, we never respect them. We are never satisfied with anything until we have had too much; then, because too much harms us, we are likely to abandon the thing altogether, rather than learn the true lesson. We work on the principle: The more of a good thing the better. Never was there a greater delusion. A little boy asked his mother: "If a teaspoonful of salts will do daddy good, why not give him the whole box and get him well in a hurry?" Too many people work on this principle in everything they do. They over-eat, over-exercise, over-bathe, over-sunbathe, etc. Lotions are not substitutes for intelligence. Only the foolish will waste their money on such preparations.