Quids in

Why is the pound (the unit of money, not of weight) colloquially called a quid? 

The Oxford English Dictionary says: 

"Late 17th century (denoting a sovereign): of obscure origin" and records quid used in 1661, citing the pseudonymous Peter Arentine’s Strange Newes from Bartholomew-Fair, or the Wanderer-Whore Discovered: “The fool lost his purse, but we knew how not; for the reckoning being suddenly brought in, his Quids were vanisht.” 

Some naive people say that quid is taken from Quidhampton, a town near Salisbury claimed to have had a mill that produced paper for Great Britain’s first banknotes. Obviously this is rubbish. Others talk of the Irish cuid, ‘portion’ or ‘share’, once used by Irish-speaking soldiers in the British army for their salary. 

I thought about it for five seconds and knew it is from the Latin quid, meaning ‘what’, specifically used in the expression quid pro quo, or ‘one thing for another’. This, I find, is considered, according to the net, to be what dons used to call the better view.