From the book KABBALAH 365 edited by Rabbi Gershon Winkler
All beings--all of them--are interconnected one within the other, and support one another, and it is impossible for any one of them to exist without the other. Likewise, there are wondrous medicines in all of the four merka'vot (vehicles of divine manifestation)--Still Beings, Sprouting Beings, Wildlife Beings, and Talking Beings.
in Sh'lah ahl M'sechet Yoma, Perek Derech Chayyim V'tocha'chat Musar, No. 29