What The Rebbe Says:
… Rambam (Hilchos Deos 6:1) states that: “Man’s inherent tendency is that his character and conduct are influenced by his friends and comrades…. Therefore a person should join together with the righteous and reside with the wise….”
There [Rambam] is speaking about a person’s character as a recipient, which is the first stage of his [development]. Immediately [thereafter], he must also become a source of influence for others, as my revered father-in-law, the Rebbe, הכ”מ, requested in his sichah printed in Kuntres Yud-Beis Tammuz, 5710, sec. 3: “See to it that you yourself are alive and make others alive.”
(Excerpt from the Rebbe’s correspondence)