Fear comes from uncertainty. When we are absolutely certain, whether of our worth or worthlessness, we are almost impervious to fear. Thus a feeling of utter unworthiness can be a source of courage.
"Ahu" are stone platforms on which many moai sit. There are 313 known ahu and 125 of these carry moai. The biggest, Ahu Tongariki is 220 m (720 ft), and had the most (15) and tallest moai.