To answer this question, take a look at Helen Keller's autobiography, The Story of My Life. In Chapter Seven, Helen talks about her teacher, Anne Sullivan, and says:

My teacher is so near to me that I scarcely think of myself apart from her. How much of my delight in all beautiful things is innate, and how much is due to her influence.

To see this influence in action, take a look at Chapter Six, in which Helen recalls some of her experiences with Anne Sullivan. She says, for example, that Anne taught her how to understand "abstract concepts," like 'love' and 'think.' This had a profound impact on Helen since it made her feel connected to other people in the world, as though there was an "invisible line" stretched between their souls and her own.

In addition, in the next chapter, Helen talks about how Anne Sullivan developed her love of the outdoors, through studying outdoors and enjoying walks together. It was also around this time that Anne taught Helen to read, an act which fostered Helen's love of learning.

Anne Sullivan, therefore, played a pivotal role in Helen's personal and educational development, which is why her influence was so important.

After being rendered deaf and blind by fever at the age of 19 months, Helen Keller was taken care of by her parents, who relentlessly searched for people who could help their daughter overcome the limitations of her disabilities. Her parents first sought the help of a local eye surgeon who referred them to Dr. Alexander Graham Bell. The famous inventor had a significant influence on Keller's life by introducing her to Anne Sullivan, a blind educator.

Sullivan agreed to teach Keller as many basic skills as she could, from learning the alphabet through sign language to developing her abilities to read and write. Sullivan taught Keller braille at a young age and helped her read advanced texts such as Shakespearean plays. As a teacher and mentor, Sullivan also influenced Keller's perspective by showing her the importance of attending to subjects she didn't enjoy, such as math, and enjoying the beauty of the outside world.

Although they never met, Keller was heavily influenced by a Norwegian girl who was also blind and deaf but nonetheless learned to speak. Keller used this ability to continue her education and became a notable speaker, going on to influence others with disabilities to achieve things they never thought possible.