"An insincere and evil friend is more to be feared than a wild beast; a wild beast may wound your body, but an evil friend will wound your mind." - Buddha
Don John is portrayed as an nefarious, jealous, and power-seeking character. He describes himself as just plain evil. Don John embodies this quote because of his efforts to break up Hero and Claudio. Don John presents himself as a friend of Claudio, but in reality, he is working against him. In Act III, Don John's plan is put into action, and Claudio believes that Hero has been unfaithful. Claudio becomes distraught and decides that he will confront Hero on the altar, therefore embarrassing her in front of the whole town. Claudio is not thinking correctly because he is so taken aback by the scene he just witnessed. As the quote says, Don John is doing more damage to Claudio than a beast could because he is hurting him mentally rather than physically. Claudio's mental pain is messing with his judgement and he is not thinking his actions through. Everything is going exactly how Don John and Borachio have planned. If Don John's plan continues to go smoothly, then he will end up hurting many people.