According to Richard Ryan, a professor of psychology in the United States, the more people seek satisfaction in material things, the less they find it there.
فكلما حككتَ مكان اللدغة شعرت بحاجة اكبر الى الحك ،‏ الى ان ينخدش الجلد وتصير اللدغة جرحا .‏