Answer :
The excerpt serves to foreshadow the manner in which Lange attempted to hide from all of her subjects.
Dorothea Lange's grandmother taught her to observe and inspect things carefully to appreciate their true beauty. She learnt the technique of hiding and making herself invisible to her subjects whom she saw on her long walks across New York. These walks also helped her get familiar with the city and she became aware of the sharp differences in the lives of the rich and the poor. This "cloak of invisibility" greatly helped the documentary photographer in capturing the human struggle in her photographs.
