“In the weeks leading up to the eruption, Landsburg visited the area tens of times in order to photographically document the changing volcano. On the morning of May 18, he was within a few miles of the summit. When the mountain exploded, Landsburg must have realized that he would not survive the rapidly approaching ash cloud, but he kept snapping pictures as long as he could. He managed to rewind the film back into its case, replace his camera in its bag, put the bag in his backpack, and then lay himself on top of the backpack in an attempt to protect its contents. Seventeen days later, Landsberg’s body was found buried in the ash with his backpack underneath. The film could be developed and has provided geologists with valuable documentation of the historic eruption.

Imagine a physicist, well versed in the laws of gravity, which he believes to be excellent approximations to the ultimate truth. One day he encounters his first helium-filled balloon, a blatant challenge to the laws he knows so well. Two courses are open to him: He can say, “Well, the laws of gravity are usually true, but not always; here is one of the exceptions.” Or he can say, “Let me see if there is any way to explain this strange phenomenon without abandoning the most basic principles of my science.” If he takes the latter course, and if he is sufficiently clever, he will eventually discover the properties of objects that are lighter than air and recognize that their behavior is in perfect harmony with existing theories of gravity. In the process, he will not only learn about helium-filled balloons; he will also come to a deeper understanding of how gravity works.
—  Steven E. Landsburg, The Armchair Economist