Definition of "vigilance"

To-night she took her accustomed place; for, during the night, no vigilance could satisfy her but her own: any eye but hers might close in momentary forgetfulness.

1837, L[etitia] E[lizabeth] L[andon], Ethel Churchill: Or, The Two Brides. […], volume III, London: Henry Colburn, […], pages 153–154

I corralled the judge, and we started off across the fields, in no very mild state of fear of that gentleman's wife, whose vigilance was seldom relaxed. And thus we came by a circuitous route to Mohair, the judge occupied by his own guilty thoughts, and I by others not less disturbing.

1897 December (indicated as 1898), Winston Churchill, chapter VIII, in The Celebrity: An Episode, New York, N.Y.: The Macmillan Company; London: Macmillan & Co., Ltd.

But you must remember, my fellow-citizens, that eternal vigilance by the people is the price of liberty, and that you must pay the price if you wish to secure the blessing.

1837 March 4, Andrew Jackson, Farewell Address