Once upon a time, people were intimately connected with measurement of their world. A foot was the length of a foot, a leap was the distance an average person could leap and so forth. Admittedly, because feet and leaps and other such units varied from place to place this was a very imprecise method but it was human and, by and large, people understood both what they were measuring and the orders of magnitude they described using such terms.

As we move into the third millennium, everyday units of measurement have become less connected to our everyday lives. The French Revolutionary metric system which reigns almost supreme throughout the world is now mostly defined, as are the more modern SI units (Système International d'Unités), by basic concepts of theoretical physics that have little real meaning for most of us. The meter no longer has anything to do with a particular fraction of the Earth's circumference; it is defined as the distance traveled by light in a specific fraction of a second. The second itself has been redefined in terms of propagation of radiation, or periodicity of atomic quantal events.