— Will Durant American historian, philosopher and writer 1885 - 1981
Context: Excellence is an art won by training and habituation: we do not act rightly because we have virtue or excellence, but we rather have these because we have acted rightly; 'these virtues are formed in man by his doing the actions'; we are what we repeatedly do. Excellence, then, is not an act but a habit: 'the good of man is a working of the soul in the way of excellence in a complete life... for as it is not one swallow or one fine day that makes a spring, so it is not one day or a short time that makes a man blessed and happy'.
p. 87. The quoted phrases within the quotation are from the Nicomachean Ethics, Book II, 4; Book I, 7.