There are many reasons, doubtless, why doctrines which are the badge of a sect retain more of their vitality than those common to all recognised sects, and why more pains are taken by teachers to keep their meaning alive; but one reason certainly is, that the peculiar doctrines are more questioned, and have to be oftener defended against open gainsayers. Both teachers and learners go to sleep at their post, as soon as there is no enemy in the field.