A psychologist was giving a lecture when he picked up an orange and said to a young man: "If I squeeze this orange as hard as I can, what would come out?" To which the boy replied: "Juice, of course!" The professional asked him again: "Do you think apple juice could come out of it?" And the young man, laughing, replied: "No!" "And grapefruit juice?" he insisted. "Nor!" the assistant denied again. It was then that the psychologist asked the following question: "Why? Why does orange juice come out when I squeeze an orange? "Well, it's an orange and that's what's inside," argued those present.