During the Exile in Babylon, three sages were condemned to be burnt to death because they refused to bow in submission to Nebuchadnezzar: Chananya, Misha’el, and Azaria.
Chazal understand that their knowledge and surety of self-sacrifice came from the plague of frogs, which resisted the natural instinct of self-preservation, and jumped into ovens and furnaces.
But what is the comparison drawn? Frogs were explicitly sent into Egyptian ovens:
וְשָׁרַץ הַיְאֹר צְפַרְדְּעִים וְעָלוּ וּבָאוּ בְּבֵיתֶךָ וּבַחֲדַר מִשְׁכָּבְךָ וְעַל מִטָּתֶךָ וּבְבֵית עֲבָדֶיךָ וּבְעַמֶּךָ וּבְתַנּוּרֶיךָ וּבְמִשְׁאֲרוֹתֶיךָ – The Nile will swarm with frogs; they will go up and come into your house, into your bedroom, upon your bed, into the house of your servants, into your people, into your ovens, and into your kneading troughs. (7:28)
What conclusions could the sages have drawn? The frogs received specific instruction, and the sages did not. What then, did they learn from the frogs?
The command to jump into ovens was a general instruction to the species of frog that were to plague Egypt. However, each individual frog could have shirked the duty, relying on other frogs to live up to the expectations. No particular frog would then need to overcome the natural instinct to survive, and none would do so! And yet they did.
This is what the Sages learnt from the frogs.
A great person does not shirk the opportunity or responsibility for self-sacrifice. On the contrary, greatness is precisely the opposite – taking advantage of such an opportunity. The quality of “self-sacrifice” doesn’t require literally putting your life at risk though. It’s as simple as putting other people and priorities first – sacrificing your sense of self.