Answer:
Midnight shakes the memory
Step-by-step explanation:
Let's try to select phrases in the excerpt that might pass that idea and judge how well they'd fit.
"Along the reaches of the street" still shows some line of thought. "Held in a lunar synthesis" doesn't, as much, but still not enough to convey what is asked. "Every street lamp that I pass" also shows some train of thought, since the author keeps going with the "beats like a fatalistic drum". Two phrases that apply well are: "Held in a lunar synthesis" and "Midnight shakes the memory". Between those two, memories that have been shaken show with much more certainty an idea of being lost in your own thoughts, being it the correct answer.
It is midnight and he is walking down an abandoned road, street lamps are flickering. Every time a light hits him, he notices them only to be lost in thoughts again by the darkness of midnight.