The Story of My Life by Helen Keller recounts many of the incidents from Helen's early life, many of which shaped her understanding of the world and life itself. It can become quite a cliche in describing the "best" incident or event as perceptions change and what is the most important occurrence today may seem less significant tomorrow. Even Helen says this herself: " many incidents of vital importance in my early education have been forgotten in the excitement of great discoveries."(Ch 1) This autobiography is meant to inspire; hence, depending on the reader's frame of mind, different things hold different levels of importance at different life stages.
One of the 'best' incidents must be Helen's description of the arrival of Ann Sullivan who is "to set my spirit free"(Ch 1) as everything else revolves around this.
It may be Helen's parents' recognition of her talents and the need to educate her, especially allowing her to become independent, providing ""all that was bright and good in my long night" (Ch 2) that is most crucial; rendering her journey to Baltimore and onward to Washington to see Alexander Graham Bell who helped Helen "pass from darkness into light" (Ch 3) as the "best" incident.
For someone who finds communicating difficult or who is misunderstood by others, Helen's eventual connection with her sister, Mildred may be the "best" after the incident when she pushes Mildred out of the cradle in which she is sleeping and only Helen's mother's quick intervention prevents a disaster,after which Helen learns the value of human relationships and is "restored to my human heritage" which up to that point has almost eluded her because when "we walk in the valley of twofold solitude we know little of the tender affections that grow out of endearing words and actions and companionship.(Ch 2)This is a significant episode in Helen's life as it begins the path to self-awareness that is Helen's saving grace.
Hence, it is a very personal choice in finding the "best" incident. There are many more than I have recorded here. Each of these however is instrumental and vital in understanding Helen's daily struggle and having an appreciation of the effort involved in making the most out of the only life she knows.