The five paragraphs Helen Keller devotes to Martha Washington are quite interesting, as they reveal Keller's unconscious racism and the legacy of slavery in this post-Civil War southern household.
Keller discusses Martha, who we find out is black, as her "companion" (but not her friend) and equates her with her dog, Belle:
In those days a little coloured girl, Martha Washington, the child of our cook, and Belle, an old setter, and a great hunter in her day, were my constant companions.
Helen talks about how she tells Martha what to do:
It pleased me to domineer over her, and she generally submitted to my tyranny rather than risk a hand-to-hand encounter.
Helen attributes Martha's submission to her being such a fierce fighter and "indifferent to consequences." But one might suspect, especially given that Martha was two or three years older than Helen, that Martha had been taught that her place was below that of a white child. Her mother, the cook, could well have once been a slave. Keller never seems to have considered that racism played a role in this unequal relationship, where the older child catered to the whims of the younger.
As far as Helen remembers it, the two of them and the dog had a good time together. Both Martha and Helen loved mischief. Helen tells of them helping in the kitchen, feeding the fowl, and once stealing a cake that the cook had just frosted and eating it by the woodpile. Helen also recalls a time they snipped off everything they could find on the porch with scissors, including each other's hair.
Although Helen seems not have realized it, it appears Martha's job was to keep Helen amused and out of other people's way. One wonders if it was as much fun for Martha as it was for Helen to be her companion.