The Olive does not Produce Oil Until it is Crushed
“A leafy olive tree beautiful with shapely fruit; amid the sound of great commotion He has set fire to it and its branches were broken (Jeremiah 11:16). Yehoshua son of Levi said: Just as the olive tree’s leaves do not fall neither in winter or summer so too Israel will always remain in this and the world to come” (BT Menakhot 53b, cf. Zohar 1:116a).
“Why is Israel compared to an olive? To teach that just as the olive does not produce its oil until it is crushed, so too Israel does not return except through suffering” (BT Menakhot 53b).