Language Of Confusion: Per-, Part I

This series is going to be super long, because the Proto Indo European per-, forward has spawned a LOT of words, most of which I’ve never looked at before. So it’s going to be busy, is what I’m saying.
 
First, the word that sent me down this rabbit hole: prove. It showed up in the thirteenth century from the Old French prover/pruver, from the classical Latin probare, to prove, which is from the PIE pro-bhwo, being in front, and that pro- is from -per. Proving is putting stuff in front? I guess I can see it on a figurative level. Proof is pretty close, showing up in the same century but from the Anglo French prove/preove, Old French proeve/prueve, and Late Latin proba, which is then from probare. There doesn’t seem to be a real reason for the V to F thing, other than some words (relief, belief) just do that. Fun fact, proof in use of alcohol is from 1705, because its degree of strength was tested (or proven).
 
Similarly, there’s approve, which showed up in the fourteenth century. That was aprover in Old French, and approbare in Latin, so there really hasn’t been much variation over the years. With the prefix ad- meaning to, approbare is literally to forward something, and figuratively it means to test something, which I guess would move it forward. There’s also improve, which showed up in the late fifteenth century, actually meaning to increase income, which of course leads to things improving. It’s from the Anglo French emprouwer, which is a mix of the prefix em-, which is causative here, and prou, which means… profit. And that’s not the end, either. Prou comes from the classical Latin prode, again, profit, the origin word for proud.
 
Yes, proud is related. It comes from the Old English prud/prute, also just proud. That’s from the Old French prud, from the adjective prouz (which actually means brave or valiant), which is from the Latin prode. And there’s also probe, which showed up in the early fifteenth century specifically meaning a flexible rod for exploring wounds or body cavities (ew). It was taken directly from the Medieval Latin proba, which is from probare. Because you’re testing the body. With a probe. Again, ew.
 
One more for today, profit, which was already mentioned a few times. It showed up in the mid thirteenth century from the Old French profit/profit and classical Latin profectus, growth, so yes, it does not come directly from the Latin word for profit. Profectus is from the verb proficere, to make progress, with facere meaning to do and the pro meaning forward, taken from per-.
 
Sources
Online Etymology Dictionary
Google Translate
Omniglot
Dictionary.com
University of Texas at Austin Linguistic Research Center
University of Texas at San Antonio’s page on Proto Indo European language
Tony Jebson’s page on the Origins of Old English
Old English-English Dictionary
Dictionary of Medieval Latin
Fordham University
Orbis Latinus