a/ex in expressions where something is/happens

[Carolus Raeticus]

Salvete!

I recently stumbled upon the expression "nulla ex parte" ("Sol nulla ex parte obscurus [est]"). This reminded of similar expressions, e.g. "a tergo", "a dextra parte", "a terra".

I do not quite understand these. I do understand "a summo" and "a imo" as these imply something coming from above or below respectively. But why did the Romans use "a" (or "ex") when it comes to tell where something is (instead of "where from").

Of course, I could always learn these expressions by heart, but I would like to understand, as these expressions seem rather counterintuitive to me.

Does anyone have an idea?

Valete,

Carolus Raeticus

[adrianus]

The positions "a tergo", "a dextra parte", "a terra" are all relative, measured against (or from) another point.
Haec loca pro ratione alii loci computantur.

[Carolus Raeticus]

Hello Adrianus!

The positions "a tergo", "a dextra parte", "a terra" are all relative, measured against (or from) another point.

But how would we express "from the right side", "from the landside", if the expressions mentioned above are already relative? Are the same expressions used both for telling "where" and "where from"?

Bye,

Carolus Raeticus

[adrianus]

But how would we express "from the right side", "from the landside", if the expressions mentioned above are already relative?

Ut credo, "e(x) dextrâ" "e(x) tergo" "e(x) terrâ" pro "out of"