Mons Lie was born in Ålen, where his father worked in farming and mining. When Mons was nine years old, he fell off a horse and broke his arm. It never fully healed, which meant that he was prevented him from doing hard manual work. Instead he received schooling in Røros, learning to read and write. Later he was given work in the mining administration office there.
At the age of 17 he came to Trondheim. Even though he did not have much in the way of formal qualifications, he had a rapid rise in his career. First he was a servant for merchants, later a clerk and manager. He was given responsibility for the forest properties of the Angell's foundations, all before he was 20. In 1777 he married for the first of three times. Due to his skills and abilities, in 1793 he was granted a legal licence for Trondheim town and the surrounding county. He practised as a procurator up to 1811, at which time he had become quite well off. Lie had acquired a reputation as a fair and watchful civil servant. He enjoyed a high reputation among people in general because he was not recruited from the bourgeoisie, and did not immediately side with the wealthy class. After 1800 he was given responsibility for fire protection in town, and in 1808 he was appointed chief city executive. His relationship to the merchant representatives in the town's controlling bodies was at times strained.
In the political discussion around the signing of the constitution in 1814 he advocated alliance with Sweden. He believed that Norway was not ready for independence, and while growing up he had found it natural to socialise and interact with Norway’s immediate neighbours to the east. This was an unpopular minority point of view. In 1817 he was finally appointed commissioner of police in Trondheim, a post he long had wanted and aimed for.
Mons Lie left some samples of poetry written in dialect. This literary tradition was carried forward in the family, and Mons is the grandfather of poet Jonas Lie (1833-1908). Jonas Lie's son, Erik Lie, published the book Naadigherren [Noble Master] in 1927. This book depicts a character with a social-climbing career clearly modelled on his great grandfather's life.
Recommended reading: Norsk biografisk leksikon [Norwegian Biographical Encyclopaedia] volume 8. 1923.