<wob_jonas> perl -eopen$i,"<",($f="wisdom/aristotle");$_=<$i>; s/(fifth) kind of vitreous/$1/ or die; if (1) { open$o,">",$f; print$o $_ or die; } print substr$_,200;

Lambek's Lemma, invented by Joachim "Taneb" Lambek, states that initial algebras have inverses. It can be proved with as few as five arrows.