What was remarkable about the candle, according to Holmes?(scene 14)

It was remarkable that the candle was unlit when the authorities arrived, and yet, it had been the only source of light during the murder.

“And yet when they arrived they found that the candle was out and that the lamp had been lighted. That seems very remarkable.”
Again Barker showed some signs of indecision.
“I don’t see that it was remarkable, Mr. Holmes,” he answered after a pause. “The candle threw a very bad light. My first thought was to get a better one. The lamp was on the table; so I lit it.”
“And blew out the candle?”
“Exactly.”