When Avraham pleads for Sodom to be spared, he speculates that perhaps fifty righteous people would make the city worth saving.
וַיֹּאמֶר ה, אִם-אֶמְצָא בִסְדֹם חֲמִשִּׁים צַדִּיקִם בְּתוֹךְ הָעִיר–וְנָשָׂאתִי לְכָל-הַמָּקוֹם, בַּעֲבוּרָם – Hashem said: “If I find in Sodom fifty righteous in the city, then I will forgive all the place for their sake.” (18:26)
The Ibn Ezra notes that the repetition of “in Sodom” and “in the city,” implies that these people are righteous in public – בְּתוֹךְ הָעִיר.
R’ Samson Raphael Hirsch teaches that righteous people live among and interact with other people, leading by example and inspiring their communities, like Avraham himself. A righteous man is not hidden away with books but is part of a community -including its sinners – as a teacher and a neighbor.
This remarkable point teaches a tremendously portable lesson about Sodom’s destruction; Sodom was not doomed because of its evil, but because no one was willing to work for its salvation. If even 10 such people had been working with the public to improve the moral state of the community, the city might have been saved.
Nechama Leibowitz notes that Jeremiah mentions the same theme:
שׁוֹטְטוּ בְּחוּצוֹת יְרוּשָׁלִַם, וּרְאוּ-נָא וּדְעוּ וּבַקְשׁוּ בִרְחוֹבוֹתֶיהָ, אִם-תִּמְצְאוּ אִישׁ, אִם-יֵשׁ עֹשֶׂה מִשְׁפָּט מְבַקֵּשׁ אֱמוּנָה–וְאֶסְלַח, לָהּ – Run through the squares of Jerusalem and search its streets; if you can find just one single man who practices justice and seeks the truth, I will forgive her! (5:1)
The Radak explains that no righteous men could be found in the streets of Jerusalem because they were too afraid to stand up for what they believed in publicly.
The Lubavitcher Rebbe said that our souls are candles God gives us to illuminate the world, like the Chanukah Menorah, which is ideally positioned by the front door or window, so that it lights up the inside of our homes, but outside as well. He famously dispatched followers to the ends of the earth based on the understanding that part and parcel of wholesome observance is seeking others out to help them find their own religious expression. The discomfort of swimming against the tide of popular culture is the sacrifice that validates how much we care about other people – if we abandon those who are wandering or lost, do we care about others at all?
R’ Mordechai Gifter taught that altruism is superior to empathy; because while empathy requires us to tune in to other people’s needs, whereas altruism requires positive outreach – Avraham had no-one to help, so he stood outside his home to find someone to take care of.
The few can save the many, so long as they care enough about their communities to get involved – בְּתוֹךְ הָעִיר / בְּחוּצוֹת יְרוּשָׁלִַם / בִרְחוֹבוֹתֶיהָ.
A single candle can dispel a lot of darkness.