A sensory details is use by the writer to connects the reader's five senses (sight, sound, smell, taste and touch) to an image or a description. The writer gives an image of ears with gray hair. From that image, the writer show us an estimated age of the character he's referring.
FDR explains that it's best to be happy with what you have, as well as the little things in life. "Joy and hope spring eternal despite harsh living conditions, thanks to American civil liberties."