Parkman believed that psychiatric institutions should reflect a residence-like setting, where patients could enjoy hobbies and socializing and participating in household chores, as permitted. Parkman thought Pitié-Salpêtrière Hospital was a good model and talked to the faculty of Massachusetts General Hospital about having a lunatic hospital connected to it. In 1817, he wrote two papers, "Remarks on Insanity" and "The Management of Lunatics" in an effort to convince the trustees of the Massachusetts General Hospital that he could supervise an asylum they were considering opening. That same year he offered to raise $16,000 for the construction of a full-size institution. Unfortunately, the trustees interpreted the offer as a proposal to fully endow the project. Later, the McLean Asylum for the Insane was established, but the trustees feared the taint of corruption if Parkman had held an appointment he had endowed. Rufus Wyman, the father of Jeffries Wyman and Morrill Wyman, who both were involved in the Parkman–Webster murder case, was appointed. Parkman retired, but continued his interest in medicine and insanity. He would visit and entertain them, he bought them an organ, and opened up his own mansions during cholera and smallpox epidemics for the treatment of patients.