What are Keller's reasons for describing the garden as the paradise of her childhood?

Helen Keller was drawn to nature. Like her father, Helen appreciated being out in nature. The garden near her house was a place of solace for her. When Helen was young, she would go to the garden when she became frustrated. She found peace there among the flowers and vines. She could not see or hear, but she used her senses of smell and touch to enjoy the garden. Helen especially loved the flowers in the garden. Roses were her favorite of all. Though she traveled to many places in her life, Helen never experienced roses like the ones at home.
The garden was like a paradise to young Helen. She experienced joy and comfort when she spent time there. Being in the garden made her happy. Helen described her time spent in the garden before Ms. Sullivan came to be her teacher:

There, too, after a fit of temper, I went to find comfort and to hide my hot face in the cool leaves and grass. What joy it was to lose myself in that garden of flowers, to wander happily from spot to spot... (The Story of My Life, Chapter I)