“Men of integrity are generally pretty obstinate in adhering to an opinion once adopted.”

Introductio ad prudentiam: Part II (1727), Gnomologia (1732)

Source: A Dictionary of Thoughts, 1891, p. 438.

Hercule Poirot
Source: The Mystery of the Blue Train (1928)

Source: Sarah de Berenger: A Novel (1879), Ch. 19, p. 224.

"Fooling the People as a Fine Art", La Follette's Magazine (April 1918)

Preface to the Second Edition (1869)
Essays in Criticism (1865)
Context: It is not in my nature, some of my critics would rather say, not in my power, to dispute on behalf of any opinion, even my own, very obstinately. To try and approach truth on one side after another, not to strive or cry, nor to persist in pressing forward, on any one side, with violence and self-will, — it is only thus, it seems to me, that mortals may hope to gain any vision of the mysterious Goddess, whom we shall never see except in outline, but only thus even in outline. He who will do nothing but fight impetuously towards her on his own, one, favourite, particular line, is inevitably destined to run his head into the folds of the black robe in which she is wrapped.

King v. Pasmore (1789), 3 T. R. 243.

Mansfield Park (1814)
Works, Mansfield Park

1005.56 http://www.rwgrayprojects.com/synergetics/s10/p0520.html#1005.50
1970s, Synergetics: Explorations in the Geometry of Thinking (1975), "Synergy" onwards