Prepared by his father, he entered Harvard College before he was twelve, receiving four years later the degree of M. A. At graduation, in 1735, he delivered the Latin salutatory oration.
For some months he taught school, studying theology and medicine, and settling in Exeter as a teacher at least as early as 1740. Although he made some attempts at preaching, he turned ultimately to business and carried on a country store.
Phillips soon accumulated a large property, chiefly through speculation in real estate and the lending of money at high rates of interest. Phillips was interested in town and state affairs and held several offices, among them that of moderator of town meeting in 1778 and 1779. He served for three years in the General Court (1771 - 73) and was colonel of the Exeter Cadets.
His chief claim to distinction, however, rests upon his philanthropies. He made liberal gifts to Dartmouth College, including a professorship of Biblical history and literature, and he became in 1773 a trustee. In 1781, shortly after the founding of Phillips Academy, Andover, he corresponded with his nephew, Samuel Phillips, regarding the establishment of a similar school in Exeter. The act of incorporation for the new institution, to be called the Phillips Exeter Academy, was dated April 3, 1781, but the school was not opened until 1783. He contributed approximately $30, 000 to the establishment and development of Phillips Academy, Andover, and gave much of his remaining fortune to the Phillips Exeter Academy.
Formal in his manners and austere by temperament, Phillips was thoroughly Puritanical in spirit and was frugal, conscientious, and religious.
Quotes from others about the person
The epitaph written for him by Principal Pearson, of Andover, said of him: "Without natural issue, he made posterity his heir. "
On August 4, 1743, he married Sarah (Emery) Gilman, a widow some years older than himself, whose first husband, Nathaniel Gilman, of Exeter, had left her more than eight thousand pounds. Mrs. Phillips died, October 9, 1765, and on November 3, 1767, he was married to the widow of Dr. Eliphalet Hale, the local physician. He had no children.