Practicing your profession

A fountain pen salesman presuaded a merchant to order 500 dozen pens. He was writing in his notebook when suddenly the merchant exclaimed, "Hold on! I'm canceling that order!" The he turned to wait on a customer. The salesman left the store perlexed and angry. Later the merchant's book keeper asked, "Why? " did you cancel that fountain pen order?" Why? " responded the merchant, "Because he talked about the fountain pens to me half an hour, using a number of forcible arguments, and then booked my order with a lead pencil. His practice did not agree with his profession.