One good measure of our apparently inexhaustible interest in Abraham Lincoln is that this year eight hundred thousand of us will be led through his house at the corner of Eighth and Jackson streets in Springfield, Illinois. So many people edge past the horsehair furniture and stomp up and down the narrow stairs that the National Park Service had to close the place down in 1987, take much of it apart, and put it back together again, newly decorated and sturdily reinforced with steel, to withstand the next generation of pilgrims.