It is easier to prepare food for a human than a silkworm," says Toshio Ito, a Japanese silkworm physiologist. Silkworms only live for about 28 days, but in that time they increase in weight 10,000 times. At the end of their short lives, they spin a cocoon. In China, I watched workers collect the cocoons and kill the silkworms with steam or hot air. They then put the cocoons into hot water to make them softer. Next, they pulled the fibers from the cocoon and spun them to make silk thread. Finally, they wove the thread into cloth on machines called looms. But why is silk so expensive? Well, it takes 110 cocoons to make a man's tie, 630 cocoons to make a blouse and 3,000 cocoons to make a heavy silk kimono. That's a lot of mulberry leaves and many hours of hard work. But many people believe its beauty is worth it. As Kokoh Moriguchi a textile artist told me, A woman is more gentle when she wears a silk kimono.