The Logic Behind the Knock: A Thousand-Year-Old 'Reasoning Game'

Winter Night Knock: Shao Yong and His Son's 'Sound Reasoning'

This is a famous case from the Plum Blossom Yijing, often considered an ancient 'reasoning game.'

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📍The story takes place on a winter evening at the hour of You (approximately 17:00–19:00)

Shao Yong and his son are warming themselves by the fire when suddenly someone knocks at the door.

The knocking is somewhat peculiar:

• First, 1 knock
• Then, 5 knocks
• Then, from outside the door, the person says they want to borrow a tool.

Shao Yong immediately signals the neighbor not to continue, then turns to his son and asks:

'You deduce what the person wants to borrow.'

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📍The Son's Reasoning: Starting from Numbers

Since the knocks are 1 + 5, the father and son use traditional numerological deduction:

• 1 corresponds to 'Qian'
• 5 corresponds to 'Xun'
• The current time 'You hour' is 10
• So: 1 + 5 + 10 = 16
• 16 ÷ 6, remainder 4, representing the fourth line moving

According to the formula:

• Primary hexagram: Upper Qian, Lower Xun → Tian Feng Gou
• Mutual hexagram: Both upper and lower are Qian
• Moving line is the fourth line

The son deduces from the hexagram's imagery of 'metal short, wood long':

'It should be a hoe.'

Because a hoe has a long wooden handle and a short metal part, matching the image.

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📍The Father's Reasoning: Beyond Numbers, Consider Context

Shao Yong shakes his head and says:

'No, he should be borrowing an axe.'

The son is puzzled: 'From the numerological deduction, both hoe and axe fit. Why do you say axe?'

Shao Yong explains:

'Reasoning cannot rely solely on numbers; you must also consider the current 'principle.'' 'It is a cold winter night. No one goes to the fields to hoe at night.' 'But at night, to burn fire for warmth, one needs to chop wood, so it is more likely he wants an axe.'

The son suddenly understands.

Sure enough, when they open the door— The neighbor indeed comes to borrow an axe.

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📍The Beauty of the Story Lies Here:

It is not just a deduction of numbers, but a judgment of principle.

• Numbers provide direction
• Hexagram imagery provides possibilities
• But the final conclusion is grounded in life logic

This is a principle that the ancients emphasized:

'Imagery comes from life; deduction must return to life.'

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📍What Can This Story Inspire in Us Today?

• Analyzing problems cannot rely solely on data; context must also be considered
• Logic must be combined with reality
• No matter how advanced the tool, it cannot replace 'understanding of life'

To some extent, this is an ancient 'audio detective puzzle' and a reasoning lesson combining 'data + common sense.'