Arnold's father was a businessman. Socially, the family was high-ranking in Norwich. When he was ten, Arnold was sent to a private school in Canterbury. His parents planned for him to go to Yale. However, after the brother and sisters died, Arnold's father started drinking, and the family lost some of its money. By the time Arnold was fourteen, his family could not pay for private education. His father also drank too much and was in too poor health to teach Arnold to work in the family business. Arnold's mother's friends made Arnold the apprentice with two of her cousins, Daniel and Joshua Lathrop, in an apothecary and general merchandise business in Norwich. His apprenticeship with the Lathrops lasted seven years.