The press of footsteps 

was as thick here; 

and the same consideration 

of the suffering he had had, 

perplexed and terrified him. 

He began to fear that all this 

intricacy in his brain would 

drive him mad; and that his 

thoughts already lost coherence 

as the footprints did, 

and were pieced on 

to one another, 

with the same trackless 

involutions, and varieties 

of indistinct shapes.

(D&S, Ch. 59)