It is plain that the promise, or extension of responsibility through time, is what chiefly distinguishes us, I will not say from savages, but from brutes and reptiles. This was noted by the shrewdness of the Old Testament, when it summed up the dark irresponsible enormity of Leviathan in the words “Will he make a pact with thee?” The promise, like the wheel, is unknown in Nature: and is the first mark of man. Referring only to human civilisation it may be said with seriousness, that in the beginning was the Word. The vow is to the man what the song is to the bird, or the bark to the dog; his voice, whereby he is known. Just as a man who cannot keep an appointment is not fit even to fight a duel, so the man who cannot keep an appointment with himself is not sane enough even for suicide. It is not easy to mention anything on which the enormous apparatus of human life can be said to depend. But if it depends on anything, it is on this frail cord, flung from the forgotten hills of yesterday to the invisible mountains of to-morrow. On that solitary string hangs everything from Armageddon to an almanac, from a successful revolution to a return ticket.
— The Appetite of Tyranny (1915).