The Tzaddik and the Rebbe

Reb Elimelech of Lizhensk taught:

"[Noach was] a Tzaddik, complete in his generations."

The Tzaddik, through the holy deeds that he performs, draws the blessed, exalted Creator down into this world. It emerges that he does a favor for his generations (i.e., for the people living in his time), for he brings them the privilege of the Divine Presence resting with them via the Tzaddik.

[Moreover], by rising to a higher level, the Tzaddik connects and elicits G–d's exalted Name in all the worlds. This is the deeper meaning of the verse, "a Tzaddik, complete in his generations"—that his complete righteousness benefited his generations.

It is written: "Noach 'made walk' with Elokim," for his righteousness even benefited the higher spiritual realms (alluded to by the divine name of Elokim). He would even bestow (G–dliness) upon them. This is the deeper meaning of the phrase, "with Elokim." This refers to the higher spiritual realms, for even there Noach would "make walk" (i.e., elicit G–dliness).

Noam Elimelech p. 5.

In my own words:

The Tzaddik's every action reveals G–dliness in the world in a way that illuminates the darkness for regular people. Moreover, when the Tzaddik rises to a new level, this brings G–dliness to be revealed in all the worlds. I.e., not only does the Tzaddik illuminate our lowly world, but he brings additional illumination to the higher spiritual realms.