"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.
What the sayer of praise is really praising is himself, by saying implicitly, my eyes are clear. Likewise, someone who criticizes is criticizing himself, saying implicitly, I can't see very well with my eyes so inflamed.