Answer:
As the phrase says "Evil can never truly hide itself" the reality hidden inside the character can not be any longer in the dark.
Step-by-step explanation:
The excerpt shows how the inner evil of Dr, Jekyll is taking over his conscious moments and showing itself out, the same way the expression implies that there is nothing real that we could eternally keep inside, it will always rise to the surface of who we are due to its deep roots in our bare soul and essence.