As it is written in the Śūraṅgama Sūtra:

It is like when someone points his finger at the moon to show it to someone else. Guided by the finger, that person should see the moon. If he looks at the finger instead and mistakes it for the moon, he loses not only the moon but the finger also. Why? It is because he mistakes the pointing finger for the bright moon.

Recently quoted by Bruce Lee, than in the movie Le Fabuleux Destin d’Amélie Poulain