Alright, let's break this down from a philosophical or even psychological perspective you might encounter in your studies:
"The perfect Dao is without difficulty, save that it avoids picking and choosing."
Think of the "Dao" as the fundamental principle or the natural flow of reality. Accessing or aligning with it isn't inherently complex. The only difficulty arises from our own mental habit of making distinctions, forming preferences, and constantly evaluating—choosing one thing over another.
"Only when you stop liking or disliking will all be clearly understood."
True clarity or objective understanding emerges when you suspend subjective biases. Your strong attachments ("liking") and aversions ("disliking") act like filters that distort your perception. Remove the filter, and you see things as they are.
"A split hair's difference, and heaven and earth are set apart!"
This highlights the profound impact of even the slightest judgment or distinction. The moment you introduce a preference, however small, you create a conceptual division. This act of separation fragments your perception of an underlying unity, creating a vast experiential gap (metaphorically, "heaven and earth").
"If you want to get the plain truth, be not concerned with right and wrong."
To perceive reality directly, unmediated by layers of interpretation, you need to step outside rigid dualistic frameworks, particularly moral or conceptual ones like "right" and "wrong." These are constructs we impose, not necessarily inherent properties of reality itself.
"The conflict between right and wrong is the sickness of the mind."
This constant internal (and often external) struggle based on forcing experiences into binary categories of "right" or "wrong" is identified as a fundamental source of mental distress, confusion, or imbalance—a sort of cognitive "sickness." It perpetuates conflict rather than understanding.
Essentially, it's arguing for a state of non-judgmental awareness as the path to true understanding and peace, suggesting that our ingrained habits of evaluation and categorization are the primary obstacles.