Making offerings is a way to counteract miserliness and cultivate generosity in the mind. When offering the set of seven water bowls, the practitioner visualizes that the water is transformed into extensive offerings of drinking water, water for washing feet, flowers, incense, perfume, food and music. Often a lighted candle is also included in these offerings.
It is considered auspicious (benefiting lifespan) to leave a light offering on the altar at all times, so these lotus lights are always left on. The lotus is a common symbol of transformation in Buddhism – something that is pure growing from muck. It also symbolizes detachment from this cyclic existence.
See Also
The Skinny on the Buddha Bowl