[Moses said to the Jewish people,] "G-d said to me, 'arise, descend quickly from here, for your people have become corrupt....'"
Devarim 9:12
When G-d told Moses to descend, He not only meant that he should ascend the mountain; He also meant that on account of the people's misdeeds, Moses would have to descend from the exalted level of Divine consciousness to which he had ascended when he received the Torah directly from G-d.
Moses clearly did not participate in the people's misdeed. Moreover, he could not even be faulted for not protesting their actions, since he was not there. Nonetheless, he was adversely affected by their sin, because the nature of the bond between a true Jewish leader and his flock is such that when they ascend, he ascends too, and when they fall, he falls too.
We are all leaders, since we all have people whom we can influence. From this incident with Moses, we see how entwined our own personal success in life is with the success of those whom we can influence. The surest way to promote our own spiritual growth is by promoting the spiritual progress of others.
From Kehot's
Daily Wisdom #2