Helen Keller wants to highlight the importance of the day Anne Sullivan entered her life. Therefore, she uses a certain amount of fanfare and hyperbole to describe it. She goes back and forth between how she recollects the scene from her adult vantage point and how she experienced it as a little girl.
The adult Keller compares it to the Israelites crossing the Red Sea to escape from slavery in Egypt, a miraculous moment that changed the destiny of this group of people. She also frames it in terms of another miraculous event, in which a voice from heaven spoke to spoke to Jesus at his baptism. She also hears a heavenly voice:
Thus I came up out of Egypt and stood before Sinai, and a power divine touched my spirit and gave it sight, so that I beheld many wonders. And from the sacred mountain I heard a voice which said, "Knowledge is love and light and vision."
Of course, this is her adult framing: at the time she did not hear a voice and did not know she was encountering a life-changing miracle.
Keller also puts us at the scene of the momentous day as she experienced it as a child. The young Helen knows something is going on because of the way her mother is bustling around, but she doesn't know what. She goes out to the porch to wait. She smells the honeysuckle and feels the warmth of the sun on her face.
The adult Helen likens Miss Sullivan's arrival to seeing a light in a harbor when you are out on a boat in a dense fog. The light tells you salvation is at hand. She describes their actual meeting in emotional, dramatic words, which again echo the coming of Christ in the words "come to reveal all things to me:"
I felt approaching footsteps. I stretched out my hand as I supposed to my mother. Some one took it, and I was caught up and held close in the arms of her who had come to reveal all things to me, and, more than all things else, to love me.
After this buildup, the initial time Helen and Miss Sullivan spend together the next day is anti-climatic. Miss Sullivan gives her a doll and tries to write the word doll and other words into her palm, but Helen doesn't understand. Unlike the adult self telling the story, the little girl self doesn't yet know that Miss Sullivan is her savior.