So far we have considered only the orthodox systems of Indian philosophy: those that acknowledge the authority of the Vedas and are designated astika. Besides these, however, India has given birth to an alternative group of systems, designated as nastika, or unorthodox (heterodox), because they reject that authority. This is not to say that they deliberately set out to deny the ideas and values expressed in the Vedas: only that they assert the right, where it seems appropriate, to modify them, disregard them, or add to them.