C.N. Douglas, comp. Forty Thousand Quotations: Prose and Poetical. 1917.

Self-defence

Self-defence is a virtue,
Sole bulwark of all right.

Byron.

To kill, I grant, is sin’s extremest gust;
But, in defence, by mercy, ’tis most just.

Shakespeare.

The smallest worm will turn, being trodden on;
And doves will peck in safeguard of their brood.

Shakespeare.