Eknath Easwaran's Commentary
Clay lamps are still used today in India, where they are lit and placed in an alcove of the shrine. Since there is no wind in the protected niche, the tongue of the flame burns without a flicker.
In the depths of your meditation, when you are concentrating on an inspirational passage such as the Prayer of Saint Francis, your mind will be like the tongue of flame in a windless place – motionless and steady. At that time you will be concentrating completely on the words of the prayer, which means that you are slowly becoming like Saint Francis in your daily conduct and consciousness. It requires enormous endeavor to do this, but through ceaseless effort every one of us can reach the state in which the mind, like the flame of the clay lamp, does not flicker or waver at all.