rosh hashana 15

what can be learnt from a silent study partner? an adversary that doesn't answer back?

but sometimes, as the poor etrog knows, it is better to leave things alone.

(Resh Lakish and R. Yohanan seem to be in disagreement about if the etrog is tithed at picking or when it is formed. But R. Yohanan is remarkable silent in the face of Resh Lakish's argument. on this page it is also noted that many people handling the etrog tree may damage the tree and affect the growth and future fruit for 3 years.)