[I]t being reasonable and just, I should have a right to destroy that which threatens me with destruction: for by the fundamental law of nature, man being to be preserved as much as possible, when all cannot be preserved, the safety of the innocent is to be preferred: and one may destroy a man who makes war upon him, or has discovered an enmity to his being, for the same reason that he may kill a Wolf or a lion.
John LockeDefects and weakness in men's understandings, as well as other faculties, come from want of a right use of their own minds; I am apt to think, the fault is generally mislaid upon nature, and there is often a complaint of want of parts, when the fault lies in want of a due improvement of them.
John LockeAll mankind... being all equal and independent, no one ought to harm another in his life, health, liberty or possessions.
John LockeHe that has his chains knocked off, and the prison doors set open to him, is perfectly at liberty, because he may either go or stay, as he best likes; though his preference be determined to stay, by the darkness of the night, or illness of the weather, or want of other lodging.
John Locke