Causal
strong strength
Narrative Connection
How these two moments in the story relate
From
Decoding the Crystal's hidden power
S20E6
·
Snakedance Part 2
To
Doctor discovers crystal’s purpose
S20E6
·
Snakedance Part 2
Why These Connect
The narrative assertion
"Nyssa’s interpretation that the lines in the pictogram represent mental energy directly informs the Doctor’s later reading, where he confirms that these lines converge at the Great Crystal, validating the decoding process they just underwent."
About Causal Connections
A directly causes B. The first event sets forces in motion that produce the second. These are the load-bearing connections of plot--remove one and the story structure collapses.