Be not content with the best book; seek sidelights from the others; have no favourites.
Inaugural Lecture on the Study of History - 1895.
The danger is not that a particular class is unfit to govern. Every class is unfit to govern.
Letter to Mary Gladstone - 24 April 1881; later published in Letters of Lord Acton to Mary Gladstone - 1913.
There is not a more perilous or immoral habit of mind than the sanctifying of success.
Lectures on Modern History - 1895, Lecture XI, The Puritan Revolution, at Project Gutenberg.
The strong man with the dagger is followed by the weak man with the sponge.
Lectures on the French Revolution - 1910. Project Gutenberg.
There is no error so monstrous that it fails to find defenders among the ablest men.
Letter to Mary Gladstone, 24 April 1881; later published in Letters of Lord Acton to Mary Gladstone - 1913.
Letter , 23 January 1861, published in Lord Acton and his Circle - 1906 by Abbot Francis Aidan Gasquet, Letter 24.
Universal History is not a burden on the memory but an illumination of the soul.
Lectures on Modern History - 895, Appendix I. at Project Gutenberg.
Power tends to corrupt; absolute power corrupts absolutely. Great men are almost always bad men.
Letter to Bishop Mandell Creighton, April 5, 1887 published in Historical Essays and Studies, edited by J. N. Figgis and R. V. Laurence - 1907.