If we knew what we were doing, it wouldn't be called research, would it?

That Space, as our mathematicians have it, is spoken of as having three dimensions, which one may call Length, Breadth, and Thickness, and is always definable by reference to three planes, each at right angles to the others.

Arriving at the end of each lunar year wasn't just a new day taking over from the previous one, but also a new year taking over from the previous one, and this was called 'first exchange'.