Thoreau writes in his journal:
Not the carpenter alone carries his rule in his pocket. Space is quite subdued to us. The meanest peasant finds in a hair of his head, or the white crescent upon his nail, the unit of measure for the distance of the fixed stars. His middle finger measures how many digits into space; he extends a few times his thumb and finger, and the continent is spanned; he stretches out his arms, and the sea is fathomed.