A man gradually identifies himself with the form of his fate; a man is, in the long run, his own circumstances.

The line proposes a paradoxical view of fate and agency: what we call “circumstances” are not merely external pressures but, over time, become inseparable from the self. Through repeated choices, habits, and interpretations, a person comes to “identify” with the pattern life takes—so that destiny is not simply imposed but partly authored. In Borges’s characteristic mode, the sentence also hints at identity as a narrative construction: the self is shaped by the stories one lives and tells, until the boundary between character and plot dissolves. The moral implication is sobering and empowering at once: to accept one’s circumstances is, in some measure, to accept oneself—and to change them may require changing the self that has grown around them.