But, you know, sometimes things just strike you in a way they never have before, and they feel all new and mysterious. That's part of what I love about etymology: discovering hidden depths in words and phrases I've known all my life. The latest phrase to catch my fancy was "by and large", spoken innocently in a radio interview, and arousing my curiosity.
Of course I know what it means. I perfectly understood the man on the radio. We use it to mean "generally" or "in most cases". But while I could get kind of a picture of either "by" or "large" used for that sense - we do use "largely" to mean almost the same thing - I couldn't see why they were together. To the internet!
Online, I discovered a most interesting history for the phrase. A more vivid rendering of this metaphor would be "against and with the wind, still able to move forward". The idiom is a sailing term, from the fact that, by shifting the angles of your (triangular) sails to almost-parallel (by) and then your (square-rigged) sails almost-perpendicular (large) to the wind, a ship can progress even when the wind is blowing opposite of the direction they want to go. According to the American Heritage Dictionary of Idioms, "By the early 1700s the term had been broadened to mean 'in one direction and another,' whence its present meaning of 'in general.' "
This is not a very technical description of the 17th-century nautical techniques, but it is beautiful. When I hear "large" in this context now, I picture a big sheet puffed full with a breeze. And "by" makes me think of a hand to a rudder or wheel, playing a dance with the wind to keep it just barely pushing them forward, maybe a bit off course, but soon to be balanced by a little shift a bit to the other side of straight.
To God be all glory.