What is the difference between "enim" and "quia"?

Question

Consider the following two phrases:

noli timere: exaudivit enim Deus vocem pueri de loco in quo est (Genesis 21:17b)

et benedicentur in semine tuo omnes gentes terrae, quia obedisti voci meae (Genesis 22:18)

As I understand them, both are used in the sense of "for/because", but quia normally appears at the beginning of a sentence, whereas enim appears second in the sentence. Is this the only relevant difference, when it comes to the for/because meaning? (They have other meanings too, but my question is not about them.)

Answer 1

Their semantic role is similar, but the syntactical one is not exactly. I would say that quia is a conjunction, enim a particle. In L&S quia is indeed called a conjunction, and enim a "demonstrative corroborative particle". Reading the two dictionary entries will shed some light on their use.

The word quia corresponds to "because" quite accurately. The word enim is more nuanced. It can be used to strengthen many assertions, similarly to vero. In addition to "because" or "for", it can stand for "certainly", "indeed", "in fact" and other. You can also use enimvero, which is stronger than enim or vero alone.

The clause introduced by quia is a subordinate one and cannot stand independently. The particle enim does not have this restriction.

To condense the comparison to a single sentence, I would say that quia is a subordinating conjunction that gives a reason and enim is a coordinating particle that gives emphasis and reason.

Answer 2

To complement the other answer: enim provides an explanation of the immediately preceding clause to the addressee; whereas quia states the actual reason why what has been said happened or is the case. Enim signalizes an epistemic cue, quia describes a causal connexion or reasons of the acting persons.