Most people say we need to eat and drink to sustain the body. But that's referring to bolstering the physical body. We may not be aware that we also need to eat the wisdom-light of the Buddha-nature. Most people don't understand this principle. A simple analogy might help explain it. People need food to keep their bodies going just as a car needs gasoline to keep its motor running. The ordinary food and drink we consume only nourishes the gross, physical body. But there are some cultivators of the Way who don't need to eat or drink and yet they can live. Why is this? Because they eat the wisdom-light of the Buddhas and for them that acts as nourishment. Even those of us who sustain ourselves with gross food also thrive on the Buddhas' efficacious nature and wisdom-light.

How does the wisdom-light of the Buddhas enter our bodies? During the daytime, we work and use up a lot of energy. At night we are very tired, so we take a rest. When we rest, all the poresin our bodies open up and connect with the wisdom-light of the Buddhas and thus we get replenished. The Buddhas' efficacious nature pours into our bodies and fills us up. The following day when we awake, we feel rested and alert, light and happy and full of energy. The revitalization not only results from letting our coarse physical bodies take a break, but also comes from being filled up with the Buddhas' light.

So then someone thinks, "If you get filled up with the Buddha-light when you sleep, then I think I'll just sleep all day long get more!" Well, that won't work. That is the wrong approach. Too much is just like not having enough. Why? Because whatever amount of wisdom-light you can hold is however much you should have and that's what you get. When you're full, you can't put any more in, just as a car can't hold any more gasoline when the tank is full. If you try to force in more gas than the tank can hold, it just runs out on the ground. Too much sleep is the Same way. You just end up with a big headache. For example, if, after you're all filled up with wisdom light of the Buddhas, you continue to sleep, then you'll start to dream. In dreaming You will use up the wisdom-light and waste it.

This entire process isn't something that people can see with their ordinary eyes. But people who cultivate the Way become sensitive to these various energy levels. That's why they often meditate. During such times they're adding gasoline and filling themselves up with Buddha-light.

Someone hears this and says, "Well, I won't sleep all the time, but if we can add wisdom-light by meditating, then perhaps I should meditate all the time. I'll add on a lot of meditation." That's also a wrong attitude. Underlying that kind of thinking is greed. Greed makes people run east and west, north and south; they run all over the place looking for things and as a result waste an immense amount of gasoline. These people end up more stupid and dull-witted. They run hither and thither looking for secret dharmas, esoteric tricks for "instant enlightenment." But because their greed is insatiable, the more they look outside, the more stupid they get. Eventually these people become mice. Mice are people who were extremely greedy in the past; now they are reborn as mice. They still harbor secrets. How do we know they have secrets? Because they only come out at night when nobody is around. They go "mousing" around doing secret things.

The principle about spiritual "gasoline" I've just explained is not a superficial analogy nor sheer metaphysical rambling. You could say it is a spiritual, divine principle, something which even the frontiers of science has yet to fathom and the best analytical minds would be hard put to understand. This is something the scientists haven't discovered and can't possibly conceive of. In fact, it's something they couldn't even envision in their dream.