It would be very delightful if your Utopia could be realized and if the nations of the earth would think of nothing but peace and commerce, and would give up quarrelling and fighting altogether. But unfortunately man is a fighting and quarrelling animal; and that this is human nature is proved by the fact that republics, where the masses govern are far more quarrelsome, and more addicted to fighting, than monarchies, which are governed by comparatively few persons.

Letter to Richard Cobden (8 January 1862), quoted in Jasper Ridley, Lord Palmerston (London: Constable, 1970), p. 590.