Why did Helen not understand the value of "tender affections and endearing words? "

The need for some communication with others forced her to make crude signs; a shake of the head meant "No" and a nod, "Yes," a pull meant "Come" and a push, "Go". She was a stranger to any abstract ideas or feelings. She once, overturned the cradle in which her little sister slept just because she loved her doll's cradle and was highly jealous of her little sister. She did this, "at this presumption on the part of one to whom as yet no tie of love bound me I grew angry. Thus, it is that 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".