Be as a cat is when stalking a mouse.
Be as a dragon is when guarding its pearl.
Investigating Chan is just like using a drill to create a hole. You must keep on drilling until you have broken through. Drilling through is known as “breaking the fundamental investigation”. Having drilled a hole through, brightness will be revealed. In this dark house, without any windows and doors, you have to use a drill to make a hole. When a hole has been made, light will shine in. When you are still ignorant and do not understand anything, it is just like being in a dark room without windows and doors. If, in using this skill to investigate Chan, you succeed in drilling through, light will shine in. This is investigating Chan.
There is another analogy. Meditation is just like “a cat stalking a mouse.” When a cat stalks a mouse, it watches the mouse-hole intently. The moment the mouse comes out, the cat pounces on it and grabs it with its paw. The mouse has no way of escaping. What is the ‘mouse’? It represents your ignorance. When you emit light, it is similar to a cat that has caught the mouse.
Yet there is another analogy. It is like “a dragon nurturing its pearl.” A dragon never strays from his gem. When two dragons fight over a pearl, they treat it as even more precious than their own lives. Hence, a dragon will think of ways and means to protect its pearl. In the same way, a Chan investigator is like a dragon that nurtures its pearl constantly in thought after thought. This is called contemplating at ease. If you can contemplate at ease, you are ever mindful of the present. However, if you cannot contemplate at ease, that means you are running away! What happens when you run away? It means you give in to false thoughts. As soon as you have false thoughts, you will not be at ease. When you do not have false thoughts, then you are at ease.
Let me give you another example. What is meditation like? It is like “a hen brooding over her eggs.” When the hen broods over her eggs, she thinks, “I am here sitting on the eggs. When the time comes, the chicks will hatch. Little chicks will definitely appear.” When you investigate Chan, it is similar to a hen brooding over her eggs. You reflect, “Oh! One day I will be enlightened. When I practice for one day, my self-nature will shine forth a bit of light. If I practice everyday, then my wisdom light will shine forth constantly. Eventually, I will want to be the same as the Buddha, not in the least bit different.” When you investigate in this way, you are just like the hen brooding over her eggs, and one day you will succeed! This is Chan investigation.