A funny accounting story

A young accountant often asked his boss for advice in writing journal entries.
The boss would always open his desk drawer, look at something for a moment and
then tell the young accountant how to make the correct journal entry. This went
on for many years. Finally the old accountant was ready to retire. The younger
accountant asked the old man, "I don't know what I'm going to do without you.
Whenever I've had a question you always knew the answer. What will I do when
you're gone? And what's in your desk drawer? Every time I ask for advice you
look in there?" The old accountant took the younger one into his office and opened
his desk drawer. There was a 3" x 5" index card.
It said: "Debits on the Left, Credits on the Right"