What does it mean to investigate the Chan topic?

什么是参话头？

When you investigate a Chan topic or “word head,” you should investigate the beginning of the phrase, not the tail end. The “word head” is what comes before language is spoken. There is no thought process involved, but merely investigation. What can investigation be compared to? It is like using a drill bit to drill a hole, or like excavating a well. Using a drill bit to make a well or to make a hole in a surface is analogous to investigating. However, drilling a well is tangible, whereas investigating is intangible. This comparison makes it easier for you to grasp the meaning. You must keep on drilling until you have broken through. Drilling through is known as “penetrating the fundamental investigation.”

你参话头，要参话头，不要参话尾。「话头」是在言语还没有说出来的时候，就是话语之头。你参话头要参这个，这时有一个思虑没有呢？没有，只是一个参。「参」就像什么呢？就像用一个锥子钻窟窿一样，又好像凿井。用锥子钻地，把本来没有窟窿的地硬钻、钻，钻出个窟窿来，钻窟窿的锥子就是「参」；这个参是无形的，你凿井钻窟窿是有形的，用有形来譬喻这无形的，你就容易明白什么是「参」。参就是硬往里头钻，钻不进去还要钻，什么时候钻透了，那就是「破本参」了。