In his Silent Illumination, Chan teacher Guo Gu briefly touches on three kinds of thought. I unpack them below and add my own practice notes.

1. Scattered thoughts: These could be called “peripheral” or “random” thoughts. Practice:

• Simply see and let go.
• These should slowly subside over time. In other words, there will likely come a time when scattered thoughts do not even arise.

2. Discursive thoughts: These are narrative-centric thoughts (e.g., “I have so much to do today.” “What was she thinking?”) Practice:

• It can be helpful to trace these back to samskaras for a time
• After a while, however, simply hold in a soft gaze and let go. Like soap bubbles gently popping
• In this sense, discursive thoughts are treated, in a time, just like scattered thoughts were. I.e., no problem at all. Carry on with the huatou.

3. Subtle thoughts = feeling tone, which is rather like an overriding mood, though often–at least initially–a hard to espy one. Practice:

• Drop down one level, so to speak, in order to see, e.g., restlessness, a sense of overriding tiredness, giddiness, or whatever.
• Experience the feeling tone very keenly–and then see right on through it.

As the practice deepens, you’ll discover that discursive thoughts and subtle thoughts (feeling tones) both allude to some nonexistent entity or other, commonly referred to as “ego.” And there is nobody home; there is no-thing there.