This is a roman book. Whilst I invite you to accompany me in a free and full investigation of one of those tenets and practices which keep asunder the Roman and the Anglican Church, I am conscious in how thankless an undertaking I have engaged, and how unwelcome to some is the task in which I call upon you to join. Many among the celebrated doctors of the Roman Church have taught their disciples to acquiesce in a view of their religious obligation widely different from the laborious and delicate office of ascertaining for themselves the soundness of the principles in which they have been brought up. It has been with many accredited teachers a favourite maxim, that individuals will most acceptably fulfil their duty by abstaining from active and personal inquiries into the foundations of their faith; and by giving an implicit credence to whatever the Roman Church pronounces to be the truth. Should this book fall into the hands of any who have adopted that maxim for the rule of their own conduct as believers, its pages will of course afford them no help; nor can they take any interest in our pursuit, or its results. Whilst, however, I am aware, that until the previous question (involving the grounds on which the Church of Rome builds her claim to be the sole, exclusive, and infallible teacher of Christians in all the doctrines of religion,) shall have been solved, many members of her body would throw aside, as preposterous, any treatise which professed to review the soundness of her instructions; I have been at the same time assured, that with many of her communion the case is far otherwise; and that instead of their being averse to all investigation, a calm, candid, and friendly, but still a free and unreserved inquiry into the disputed articles of their creed, is an object of their sincere desire. On this ground I trust some preliminary reflections upon the duty of proving all things, with a view of holding the more fast and sure what is good, may be considered as neither superfluous nor out of place.