It is dark because Barnardo has trouble seeing the other guard.
This scene takes place at midnight and it is so dark Barnardo cannot see the other guard. Barnardo shows up for his shift, but he can't clearly make out who Francisco is. Francisco has the same problem because instead of answering Barnardo he tells him to identify himself first. They get it figured out and Barnardo begins his shift.
Answer:
Gulliver was a surgeon.
Explanation:
When his apprenticeship ends, he studies physics at Leyden. He then becomes a surgeon aboard a ship called the Swallow for three years. Afterward, he settles in London, working as a doctor, and marries a woman named Mary Burton.
The resolution: All spiders' descend from Arachne, and as the Greeks watched them spinning their thread fine, they remembered the competition and thought it was not right for even the best men to claim equally with the gods.