During practice, a person may perceive that the world is beautiful and that everyone is a Buddha. He might think he has seen Buddha-nature, but he has not. Everything has Buddh-nature, but Buddha-nature is constantly changing and is without quality or form. The ordinary mind is incapable of perceiving it. A flower has Buddha-nature, but we view it with the mind of attachment, so our experience is not a true perception of Buddha-nature. No matter how wonderous an experience may feel while we are meditating, it is not an experience of Buddha-nature, because we are still thinking and clinging to our ideas and perceptions.
The Heart Sutra says, "Form is not other than emptiness, and emptiness not other than form. Form is precisely emptiness, and emptiness is precisely form. So also are sensation, perception, volition and consciousness." There are no sense organs, and there are no sense objects. They are illusory. Therefore, anything that arises from their interaction is also illusory. How can it be Buddha-nature?
Not perceiving a single dharma: this is Tathagata.
Only then can one be called the Supreme Observer.
With this realization karmic obstacles are innately empty.
Without realization, past debts must be paid off.
The first line in the stanza above is the fundamental teaching of Ch'an Buddhism. If you are free from any attachment, then you have seen the Tathagata ─ in fact, you are the Tathagata. Many of my students say that it is not difficult to see one's self-nature; that it is actually easy to become enlightened. They are right. It does not even take a second. All you have to do is drop the past, drop the future, and drop the present moment. Easy, isn't it?