The eraser is important because it allows school children and other people to make notes in pencil, even if they make mistakes. The eraser also allows people to make beautiful pencil drawings and to correct errors. Figuratively, the concept of an eraser inspires people. It is the idea that mistakes are not permanent and that people can start over again.
WIthout the eraser, it was a lot harder to change something you had written down or drawn. Beyond the revolutionary change for writers, the eraser revolutionized the works of art that artist could create. It allowed for better detail in graphite design and helped to increase the amount of shading.
The eraser is an essential invention because it enhances the tools of writers and artists to give them more freedom. Because of the eraser, the markings made by writers and artists with pens and pencils are not permanent, as they they can be erased with an eraser and the work can be recreated. The eraser gives writers and artists the freedom to make mistakes, change their minds, and, in turn, make better creations.
Erasers as we know them today are a relatively modern invention. But erasers as a general category are age-old. The ancient Greeks and Romans relied on palimpsests and smoothable wax tablets to ensure erasability. Those gave way, eventually, to White-Out and Photoshop's "magic eraser" tool and, of course, the ultimate undoer of deeds: the delete key. But erasers are far from obsolescence -- just as writing itself is far from obsolescence.