The State Seal, adopted by Governor John Hancock and the Council on December 13, 1780 and made official by the General Court on June 4, 1885, is circular and bears a representation of the arms of the Commonwealth encircled with the words, "Sigillum Reipublicae Massachusettensis" (Seal of the Republic of Massachusetts). The final form of the seal was determined by a statewide contest.
The arms, according to legislative enactment, consist of "a shield having a blue field or surface with an Indian thereon, dressed in a shirt and moccasins, holding in his right hand a bow, and in his left hand an arrow, point downward, all of gold; and, in the upper corner of the field, above his right arm, a silver star with five points. The crest is a wreath of blue and gold, on which in gold is a right arm, bent at the elbow, clothed and ruffled, with the hand grasping a broadsword". The shield's shape is called "Plantagenet"; the Native American model used was of the Algonquin nation; the arrow points downward to indicate that the Indian is peaceful; and the star indicates that Massachusetts was one of the original thirteen states; it was sixth. The sword illustrates the Latin motto that is written in gold on a blue ribbon around the bottom of the shield: "Ense petit placidam sub libertate quietem". This is the second of two lines written about 1659 by Algernon Sydney, English soldier and politician, in the Book of Mottoes in the King's Library in Copenhagen, Denmark. It was adopted in 1775 by the Provincial Congress and means, "By the sword we seek peace, but peace only under liberty".
The State Flag is white, bearing on both sides a representation of the coat of arms like the state seal (except that the five-pointed star is white instead of silver). It was approved in its final form on July 3, 1971; before that, the obverse side depicted a green pine tree.
Source - CIS: MA State Symbols