Later writers declare that "to him who can compute the course of the sun and the revolution of the planets and neglects to do so, may be applied the words of the prophet (Isa. v. 12), 'They regard not the work of the Lord, neither consider the operation of his hands.'" To pay attention to the course of the sun and to the revolution of the planets is a religious injunction; for such is the import of the words (Deut. iv. 6), "This is your wisdom and your understanding in the sight of the nations" (Shab.