This seemingly technical change fit with Sartre's native predisposition to think of subjectivity as central: a conscious person is always immersed in a world where his or her task is to make himself concrete. A "person" is not an unchanging, central essence, but a fluid construct that continually re-arises as an interaction among a person's consciousness, his physiology and history, the material world, and other people. This view itself supported Sartre's vision of people as fundamentally both doomed and free to live lives of commitment and creativity.