Think of what your skin, 'the most visible of all bodily organs and the only body tissue that is exposed to dry air, does to serve you:

• With its fifteen feet of blood vessels per square inch, your skin helps to regulate your body temperature, making it possible for you to adjust to extremes of cold and heat.

• The large integument that covers your body-what we call skin-represents the first line of defense against harmful germs that constantly try to break through and invade your tissues.

• Despite its soft and elastic appearance, your skin is tough enough to withstand a variety of shocks and blows, acting as a cushion to protect your deeper, more vital organs from harm.

• This porous yet leakproof organ is a protective barrier between your internal body systems and the hostile environ­ment, preventing poisonous chemicals from penetrating your deeper tissues. At the same time, it prevents the outward loss of water, blood, minerals, hormones, and other essential body fluids. A genuine waterproof sac!

• Recent advances in dermatologic research have shown that your skin helps to metabolize and detoxify certain drugs and potentially dangerous environmental chemicals. If a harm­ful substance lands on the skin and begins to penetrate, various enzymes in the skin will break it down into harmless constituents.

• Skin cells produce substances-interferons and inter­leukins-known to be important to the immune defense system.

• The skin is your largest organ of sensation, allowing you to perceive heat and cold and various tactile impressions, such as pain. It is the principal organ of communication between you and your environment-the "switchboard" that receives and transmits such information as "the stove is hot," "that knife is sharp," "this pillow is soft."

• It is an organ of excretion, a vast garbage disposal system continually eliminating body wastes through more than two million sweat pores.

• Your skin protects you against the harmful effects of the sun's rays by absorbing them and converting them into dark pigment (tan) to prevent further damage.

• Your skin is supplied with oil glands-100 per square inch-which secrete sebum, the oily material responsible for maintaining the resiliency and elasticity of the skin surface.

• The skin acts as a storage house for water as well as for various nutriments, such as sugar and calcium.

• It helps in the production of vitamin D (which is really a hormone). This controls the absorption of calcium and phosphorus-minerals vital for the development of strong bones and for the prevention of rickets.

• Your skin is a mirror of what occurs below the surface-a warning signal of systemic diseases, such as diabetes, shingles, leukemia, and cancer, which often manifest themselves as skin problems long before there is positive evidence of these internal conditions.

• Finally, your "decorative wrapping" is endowed with a special capacity to reflect human passions and sentiment. As a mirror of emotions the skin is without peer. Livid with rage, pale with fright, blushing with shame. The sweating palm, the anxious pallor. All are release mechanisms of the skin that express combinations of inner feelings and skin reactions to tension, anxiety, and stress.

This, then, is your skin-"the envelope that encloses the letter of your biologic destiny" -that remarkable apparatus that spends a lifetime helping you adjust to your environment.

But we are not kind to our skin. We abuse it. And although we spend $20 billion a year on skin care and cosmetics, 'we do not understand it. Only when the itching or burning or pain become unbearable or when the cosmetic disfigurement becomes embar­rassing do we begin to take it seriously.