Never forget your past. It's your best teacher.

After eating, he gave $5 to the waiter as a tip. The waiter had a strange feeling on his face after the tip. Gates realized and asked "What happened?" The waiter replied "I'm just amazed because on the same table, your son gave a tip of $500 but as his father, the richest man on earth, only gave $5? Gates smiled and replied "He is the son of the world's richest man, but I am a son of a wood cutter."