Jack stole a check made out to the order of Bertha. Jack forged Bertha's name on the back and made the instrument payable to himself. Jack then transferred the check to Sun for cash by signing his name on the back of the check in Sun's presence. Sun was unaware of any of the facts surrounding the theft or forged indorsement and presented the check for payment. Central County Bank, the drawee bank, paid it. Who will bear the loss? Explain.