to rub / to grind / to polish / to sharpen / to wear down / to die out / to waste time / to pester / to insist
磨
=
石
+
麻
:
Mahatma Gandhi (m) has been tied down in the observatory's kitchen (o2) with ropes made of hemp (麻). He uses a stone (石) to patiently rub (磨) through the ropes.