because it ranks below the masculine plural. He used the dual for the eyes and the lips because the eyes are the heart’s sentinels, and no bodily organs are more closely connected to the heart than the eyes. Hence He mentions them together in His words:

“And We turn their hearts and eyes away.”

“In which hearts and eyes will turn about.”

“And when eyes grew wild and hearts reached the throats.”

“Hearts that Day will tremble.”

“Their eyes will be downcast.”

This is also because both possess sight: the heart’s outward vision is through the eyes, while its inward vision is through itself alone. Likewise, the tongue is the male, and the two lips are its female counterpart.