One "may know the temper of the City by him and can tell how matters go".
Again, the fear of reversal of power. Pepys want to see the warning signs early.
Reminded of the Taoist / I Ching notion of incipience: learning to spot the earliest signs of change.
https://www2.kenyon.edu/Depts/Religion/Fac/Adler/Writings/Divination.htm#INCIPIENCE