 Yet for Strauss the serious argument with which revelation challenges philosophy is not epistemological but moral. This is not to deny the importance of the pursuit of truth for Strauss, but it is to return to his criticism of the modern depreciation of pre-scientific or pre-philosophical knowledge. Again, Strauss is a critic of the Enlightenment’s view of the self-sufficiency of reason. If philosophy is to have critical potential, argues Strauss, philosophy must be skeptical even of itself. This means that philosophers should not only tolerate religion for their own instrumental purposes but that philosophy is challenged by revelation, understood as law and not as knowledge, on moral grounds.