The light dispels the darkness.
Ignorance is like a 'darkness' of the mind.
A candle is a symbol of the Buddha's teaching - the 'light' of truth that dispels the darkness of ignorance. As a flame can pass from one candle to another, so too can the truth be given from one person to another. The most common use of fire in religious practice is as candles or lamps and these can be seen on most Buddhist shrines. It is interesting to note the way the Buddha presented fire as a symbol in relation to the Brahminic society of his time. The Brahmins used the maintenance of fire, both domestic and ritual, and the fire sacrifice as a central part of their faith and life.