What is the difference between ac (or atque) and et? And how do I know when to use atque instead of just ac?
It seems that ac "binds more tightly" than et. Is this true? Or is the difference between ac (or atque) and et the conjunctive analogue of the difference between vel and aut?
Atque, according to L&S, means
a copulative particle, and also, and besides, and even, and
According to Bennett's New Latin Grammar ch. 6 §"Coordinate Conjunctions", "atque is used before vowels and consonants; ac never before vowels, and seldom before c, g, qu."
L&S continue, saying that atque
indicat[es] a close internal connection between single words or whole clauses; while et designates an external connection of diff. objects with each other
So, it seems these would make sense:
mulier ac mater
(a woman and also a mother ← related)
and
pater et arbor
(a father and a tree ← unrelated)
Bennett also mentions that -que binds more tightly than atque.
It seems this analogy would hold:
vel : aut :: atque : et
"inclusive disjunction" : "exclusive disjunction" :: "inclusive conjunction" : "exclusive conjunction"
(Interestingly, L&S also says vel was sometimes used in a "purely disjunctive sense," so there is some evolution in these "or" words.)
There is a long and very thorough explanation under ‘and’ in Smith & Hall’s Copious & Critical English-Latin Dictionary, which is readily available in various forms. (The authors also refer the reader to Allen’s Doctrina Cop. Ling. Latinae, which I have not been able to trace, but is probably 19th century and available in specialised academic libraries.)
