"By the Bye": Etymology and Usage [duplicate]

In India we frequently use this term as a substitute for 'By the way'. Is the usage as popular in other countries? Can someone throw some light on the etymology?

Solution 1:

According to Etymonline, by with the sense of secondary course as opposed to main course comes from Old English. This is also the meaning of the second by (also spelled bye) in the phrase by the by, which dates from the 1610s.

This link shows that by the way is a lot more common than by the by.

Solution 2:

You may know the phrase "highways and byways" - a byway or a by is (an old word for) a side road, less important than a main road.

Imagine the course of a conversation as going along a road. You may detour from time to time, leaving the "way" to talk about something else. "By the way," you might start that detour. The plan is to eventually return to the main topic you were discussing, but you need to mention something that's occurred to you and you might otherwise forget it. Now what if you detoured from the detour? That would by "by the by", wouldn't it?

That's your origin. Both "by the way" and "by the by" have now become stock phrases and can be used interchangeably without regard to whether you are experiencing your first detour from the main "way" of the conversation, or a detour from a detour from a detour...

Solution 3:

I saw this expression the first time on Frankenstein by Mary Shelley (1818), it is written 'by the bye'. It was probably of common usage in Great Britain during the 19th century.

Also it is contained in Northanger Abbey written by Jane Austen, also spelled 'by the bye'. Austen's novel was finished in 1803, though it wasn't published until 1818.