Apart from the trivial constant functions then, singularities are a fact of life, and we must learn to live with them.

-----Arfken, Weber, and Harris, Mathematical Methods for Physicists 7th ed, page 490


The shell has no recycle bin or trashcan. After you remove a file, it's gone forever.

-----Richard Blum, Christine Bresnahan, Linux Command Line and Shell Scripting Bible 3rd ed, page 114