Whilst the greatest effort has been made to ensure the quality of this text, due to the historical nature of this content, in some rare cases there may be minor issues with legibility. The recently published selection of Lord Acton's letters has increased our knowledge of his attitude toward the Infallibility Decree; but the entire omission of correspondence during ten most critical years of the struggle suggests, what other considerations endorse, that there is yet considerably more remaining unrevealed.