The passage discusses the powers exercised by architects as agents in agency relationships. It states that unless otherwise specified in a contract, architects generally have limited authority as agents. Architects' power and authority are determined by general agency law and the terms of their contracts. The agency relationship can be terminated in several ways, such as by agreement of the parties, revocation of authority, death of a party, completion of the task, or expiration of time. The statement that architects usually have limited authority as agents reflects the general principles of agency law.