On the Huatou

Investigating the huatou means to investigate a saying, that is, to comprehend the true meaning of that saying. Investigating the principle within a saying carries the same implication—it is the desire to understand the true meaning of that saying. In the practice of investigation, there is relatively little superficial thinking by the conscious mind; the mental activity is primarily profound mental activity at a deep inner level. The mind is both focused and profound, enabling it to explore the essence and deep significance of a saying. When concentration is shallow, this cannot be achieved.