Who does Solomon Northrop identify and experience as a free man influence his actions when kidnapped and enslaved

From the text:

But the most prominent of the four, was as a man named Arthur. As the lighter approached, he struggled stoutly with his keepers. It was with main force that he was dragged aboard the brig. He protested, in a loud voice, against the treatment he was receiving, and demanded to be released. His face was swollen, and covered with wounds and bruises, and, indeed, one side of it was a complete raw sore. He was forced, with all haste, down the hatchway into the hold. I caught an outline of his story as he was borne struggling along, of which he afterwards gave me a more full relation, and it was as follows: He had long resided in the city of Norfolk, and was a free man. He had a family living there, and was a mason by trade. Having been unusually detained, he was returning late one night to his house in the suburbs of the city, when he was attacked by a gang of persons in an unfrequented street. He fought until his strength failed him. Overpowered at last, he was gagged and bound with ropes, and beaten, until he became insensible. For several days they secreted him in the slave pen at Norfolk—a very common establishment, it appears, in the cities of the South. The night before, he had been taken out and put on board the lighter, which, pushing out from shore, had awaited our arrival. For some time he continued his protestations, and was altogether irreconcilable. At length, however, he became silent. He sank into a gloomy and thoughtful mood, and appeared to be counseling with himself.