BUT A PASSENGER. Chloroplasts and mitochondria, the indispensable powerhouses of every cell, and perhaps even the very nucleus, let alone our microbiome within, are likely all of microbial origin. As much as originating from apes hurt Victorian religious sensibilities, this new worldview would have shattered them.
http://www.poets.org/poetsorg/poem/force-through-green-fuse-drives-flower