When you say that phrase, you are saying that you found a fact from a reliable source, such as a website, dictionary, encyclopedia, etc.
Answer:
It contrasts the fear he feels about becoming Hyde with the peace he feels when safe at home.
Explanation:
The letter of Dr. Jekyll helped to show the reader of the challenges he encountered and his utmost fear which he feels whenever he transform into Hyde. <em>This is because of the brute force which he exhibit and the destruction associated with it in direct comparison to when he is his normal self as a doctor and at the comfort of his home.</em>