Always deceived in fact by his own wishes, and regardless of little besides his own convenience.

1971: What do you call that animal that goes backward and forward, head at each end? —Amphisbaena. A kind of lizard. It doesn't exist. — Anthony Burgess, M/F (Penguin 2004, p. 109)

It is clear that overfilters and underfilters are dual in the sense of the duality principle.

A group of children amusing themselves with pushing stones from the top [of the cliff], and watching as they plunged into the lake.