“There are many types of dwarfism, but the worst is the one who cannot respect others, because he does not know how to respect himself.”

Lectures on the English Poets http://www.gutenberg.org/files/16209/16209.txt (1818), Lecture I, "On Poetry in General"
Context: Poetry is the universal language which the heart holds with nature and itself. He who has a contempt for poetry, cannot have much respect for himself, or for anything else.

El que no se hallare con ánimo de sufrir apele al retiro de sí mismo, si es que aun a sí mismo se ha de poder tolerar.
Maxim 159 (p. 90)
The Art of Worldly Wisdom (1647)

No. 104 (16 March 1751)
The Rambler (1750–1752)

Speech in the House of Commons, June 10, 1941 "Defence of Crete" http://hansard.millbanksystems.com/commons/1941/jun/10/defence-of-crete#column_152, in The Churchill War Papers : 1941 (1993), Churchill/Gilbert, Norton, p. 785
The Second World War (1939–1945)
Context: I must point out … that the British nation is unique in this respect. They are the only people who like to be told how bad things are, who like to be told the worst, and like to be told that they are very likely to get much worse in the future and must prepare themselves for further reverses.

Il n'est possible d'aimer et d'être juste que si l'on connaît l'empire de la force et si l'on sait ne pas le respecter.
Source: Simone Weil : An Anthology (1986), The Iliad or The Poem of Force (1940-1941), p. 192

Source: The Prince (1513), Ch. 14; translated by W. K. Marriot

Source: Angels & Demons

Variant: Relationship Principle 10
You can tell how much someone respects you by how much he respects your opinion. If he doesn't respect your opinion, he won't respect you.
Source: Why Men Marry Bitches: A Woman's Guide to Winning Her Man's Heart

From 'Michael Angelo' (published posthumously), as included in The poetical works, Houghton Mifflin (1887), p. 316.