Physicists have determined that even the most solid and heavy mass of matter we see is mostly empty space. But at the submicroscopic level, specks of matter scattered through a vast emptiness have such incredible density and weight, and are linked to one another by such powerful forces, that together they produce all the properties of concrete, cast iron and solid rock. In much the same way, specks of knowledge are scattered through a vast emptiness of ignorance, and everything depends upon how solid the individual specks of knowledge are, and on how powerfully linked and coordinated they are with one another.

Thomas Sowell