Today we think of someone who is eccentric as unusual in their behavior.
In fact the word eccentric is a little like the phrases “off his rocker” or “out of his tree.” It was originally a metaphor.
At first eccentric was an astronomical or geometrical term and was contrasted with concentric so that concentric circles shared the same center while eccentric circles did not.
The orbit of the earth around the sun is eccentric because the orbit is slightly elliptical and so has effectively has two centres (neither of them the centre of the sun).
The word existed in Latin and Greek as well as French, German, Italian and Spanish and appeared in English in 1551.
It wasn't until 130 years later in 1685 that it's “off centre” meaning was applied to a personality and the first application held a kindly tone of an old codger. In tribute, the then recently dead Anthony Ashley Cooper was called “the brightest yet the most eccentric soul.” It has been said that rich people can be eccentric when the poor are merely crazy and this was certainly true of Cooper. Not only had he been England's Chancellor of the Exchequer and Lord Chancellor—the equivalent of the Treasury Secretary and Attorney General respectively—but he was made an Earl and a Barron twice over and with seven of his friends owned the entire landmass of what later became the States of North and South Carolina. Despite all this he didn't get on with all the other power brokers in England at the time and had to flee the country for fear of arrest.
