(with apologies to Joyce Kilmer)
I think that I shall never see
A graph as lovely as a tree.
A tree whose thick, strong root is prest
Against the lower bound at rest;
A tree that looks a little strange
While its data does self arrange;
A tree that may grow up or out
But never round and round about;
Upon whose path constraint is lain
To go forward or back again.
Graphs are made by fools like me,
But only math can make a tree.
~ Jean Bauer