When Benjace tells True Son that Whites are not really free, he is referring to the fact that Whites are slaves to their possessions.
The concept of property was not one that True Son understood in his Indian life. He did not understand the customs of the White Men.
It led, he knew, to where men of their own volition constrained themselves with heavy clothing like harness, where men chose to be slaves to their own or another’s property and followed empty and desolate lives… (p. 136)
True Son appreciates the wild, the woods, and free and open country. He likes the beautiful village of the Indians, and the sanctuary of the woods.
The reaction of True Son to the White Man’s ways is an interesting one. It shows that he has completely internalized the logic and lifestyle of his adopted people. The Indians do have a point, for as the familiar saying goes: we do not own our things, they own us.