Great visual midrash from @thelucidreams:
On Sanhedrin 4:5:
לְלַמֶּדְךָ, שֶׁכָּל הַמְאַבֵּד נֶפֶשׁ אַחַת, מַעֲלֶה עָלָיו הַכָּתוּב כְּאִלּוּ אִבֵּד עוֹלָם מָלֵא. וְכָל הַמְקַיֵּם נֶפֶשׁ אַחַת, מַעֲלֶה עָלָיו הַכָּתוּב כְּאִלּוּ קִיֵּם עוֹלָם מָלֵא
...to teach you that whoever destroys a single life is considered by the Torah to have destroyed an entire world; and whoever saves a single life is considered by the Torah to have saved an entire world...