Maimonides' attitude to animals in his ethical teachings is not the same in all his works. His cosmological outlook changed over the years, as shown in the justification he gives for the existence of animals. In a youthful work he presents a teleological, anthropocentric viewpoint, according to which animals are merely a means to an end and were created solely to serve man. However, in The Guide of the Perplexed, written in his old age, he argues that every creature was created for its own sake, since existence is good in itself. Another difference is the expansion of his rationalistic approach to the precepts of the Torah. Only in his late works does he argue that every divine command can be explained. As a consequence, one finds in The Guide of the Perplexed ethical explanations of precepts concerning animals, as well as the argument that there is sometimes no difference between the suffering of animals and human beings. In his earlier works, however, he had stated that such precepts were entirely arbitrary.