 … The second reason is that the human soul, since it is changeable and susceptible to error, cannot be rectified to save it from swerving into error by anything that is just as changeable as itself, or even more; therefore, any exemplar that it receives from natural things is necessarily just as changeable as itself, or even more, since it is of an inferior nature, whence it cannot rectify the soul so that it would persist in the infallible truth.