Finch clearly articulates here why he’s unwilling to have his mental illness diagnosed—whatever the diagnosis might be. He equates a mental health diagnosis with the person being “crazy,” and he also insists that being diagnosed means that a person’s identity then centers entirely around that diagnosis. Essentially, Finch clings tightly to his desire to be normal—and his desire to be himself, whoever that might be. Mr. Embry’s choice to bring up the possibility of bipolar disorder also shows Finch that he can’t trust Mr. Embry. In his mind, Mr. Embry wants to take away his individuality and is looking for an excuse to write Finch off as crazy.