If this story is about Mary Shelly's Frankenstein, the aspect of life that brings the monster sheer joy is the permission granted by his maker for him and his kind to go to South America and never harm a human again.
The lines that proves the mentioned scene are found in Chapter 17 of the story..
I believe the answer is: The coming of spring with its colors and smells
Ever since the monster is created, he always hated himself for his existence, and so do other people who judge the monster from his appearance alone.
But in the story, the author mentioned that the monster always find solace in soft colors and smells of a springtime forest, which help him to survive his suffering.
