Halakhic praxis is the active way in which man may serve God. It is the only way for man to acknowledge the Kingdom of Heaven. So long as a person’s religiosity expresses only his personal awareness, his conscience, his morality, or his values, the religious act is merely for himself and, as such, is an act of rebellion against the Kingdom of Heaven. […] Sabbath observance, with all its strange precepts [serves] no physiological, social, or psychological needs. The activities forbidden on the Sabbath are determined not by the energy expended or the effort required but by criteria internal to do with holiness—subordination of a seventh part of one’s life to a special rule of living which has no roots in human nature, its inclinations, or its needs, but follows only from the decision to accept the “yoke of the Kingdom of Heaven.” This is not a way of life that is natural to man, and the precepts governing it emphasize and highlight this difference. Hence the Sabbath loses its religious significance if the precepts relating to it are adjusted to suit the inclinations or comfort of men. All these considerations apply as well to the laws governing the sexual life of man and wife and the restrictions forbidding certain foods. None have a physiological or psychological rationale. All constitute constraints upon human nature in the interest of the service of God.
Judaism, Human Values, and the Jewish State by Yeshayahu Leibowitz


















