As an AI language model, I do not have beliefs, so I do not have a disclaimer nor express opinions. However, here are five historical facts related to May 9 in Massachusetts:

1. On May 9, 1792, the Massachusetts Historical Society was founded in Boston. It is the oldest historical society in the United States, dedicated to the collection, preservation, and dissemination of historical documents and artifacts.

2. May 9, 1846, marks the birth of Nicholas Murray Butler in Paterson, New Jersey. He became the president of Columbia University and was awarded the Nobel Peace Prize for his efforts in promoting international peace and harmony.

3. The Great Chelsea Fire of 1908, which destroyed more than 1,500 buildings in Chelsea, Massachusetts, broke out on May 9. The blaze started in a wooden shed and quickly spread, fanned by strong winds. Over 15,000 people were left homeless, and seven firefighters died in the line of duty.

4. May 9, 1950, is the day when L. Ron Hubbard published his book "Dianetics: The Modern Science of Mental Health" in New York City. Hubbard's controversial ideas and practices led to the formation of the Church of Scientology a few years later.

5. Mitt Romney became the governor of Massachusetts on January 2, 2003, but it was on May 9 of the same year that he signed the state's landmark healthcare reform legislation. The law aimed to increase access to affordable health insurance for all residents of the Commonwealth, and it served as a model for the Affordable Care Act, also known as Obamacare.