Okay, I know that a cleric's Divine Focus is supposed to be his or her holy symbol, or at least that's how I interpreted the rules.
However, a couple of spells are confusing me.
For example, the Light spell says Components V, M/DF (a firefly). As well, the Summon Monster I spell says Components V, S, F/DF (a tiny bag and a small candle). Does this mean Light replaces the use of the holy symbol with the firefly, or does it eschew the firefly and focus through the holy symbol?