Post History

What did the etymons of “on by + out, over, up” mean?

1. What did the etymons of  "on by out", "on by up", "on by over" mean? 

2. Why did Old English tack and jam these different prepositions together? E.g. didn't *ufan* alone mean "above"? Why prefix it with *a-* and *-b-* that appear to conribute nothing to the meaning? 


>### about  [OE]

>*About* in Old English times meant
‘around the outside of’; it did not develop its
commonest present-day meaning, ‘concerning’,
until the 13th century. In its earliest incarnation
it was *onbūtan*, a compound made up of *on* and
*būtan* ‘outside’ (this is the same word as modern
English *but*, which was itself originally a
compound, formed from the ancestors of by and
out – so broken down into its ultimate
constituents, **_about_ is _on by out_**).        
→ BUT, BY, OUT   

>### above [OE]

>As in the case of *about*, the *a-* in
*above* represents on and the *-b-* element
represents *by*; *above* (Old English *abufan*) is a
compound based on Old English *ufan*. This
meant both ‘on top’ and ‘down from above’; it is
related to *over*, and is probably descended from
a hypothetical West Germanic ancestor _*ufana_,
whose *uf-* element eventually became modern
English *up*. So in a sense, ***above* means ‘on by
up’ or ‘on by over’**.    
→ BY, ON, UP

*Word Origins* (2005 2e) by John Ayto. p 2.