Ditch on either side of the road
The "ditch on either side of the road" is an almost koan-like aphorism. It's an extension of the idea of the 'narrow way', and expresses the idea that there are two opposite ways of erring when considering a topic. It's also often invoked when discussing the balance between liberty and license - over scrupulousness vs. lasciviousness.
Example: “Some think all things should be suffered, and they are loose and cause divisions on the one hand. Others think nothing is to be suffered, and these are rigid and cause divisions on the other hand” (Burroughs, Irenicum, p. 69).
I just heard a better version! Someone said their grandfather used to say, "There's two miles of ditch for every mile of road."