A paean to prokaryotes. Out of sight, out of mind is never a good rule by which to live, and it's not a good rule for us to use with regard to the unseen prokaryotic life around us.Prokaryotes play an immense role in shaping our world, and in shaping ourselves.To ignore them is both to endanger our health and to fail to understand our world. This essay attempts to review some of the larger-scale evidence for that claim. paean to prokaryotes. Out of sight, out of mind is never a good rule by which to live, and it's not a good rule for us to use with regard to the unseen prokaryotic life around us.