Paper is one of the most important products ever invented by man. The invention of paper meant that more people could be educated because more books could be printed. Paper provided an important way to communicate with knowledge. Paper is very good for keeping you warm. Houses are often insulated( 隔热 )with paper. You perhaps seen homeless men sleep on a large number of newspapers. They are insulating themselves from the cold. In Finland , in winter it is sometimes 40 degrees below zero. The farmers wear paper boots in the snow. Nothing could be warmer.