William Wordsworth, from The Prelude: There are in our existence spots of time, That with distinct pre-eminence retain A renovating virtue, whence–depressed By false opinion and contentious thought, Or aught of heavier or more deadly weight, In trivial occupations, and the round Of ordinary intercourse–our minds Are nourished and invisibly repaired; A virtue, by which pleasure is enhanced, That penetrates, enables us to mount, When high, more high, and lifts us up when fallen.
Flow is the mental state of operation in which a person performing an activity is fully immersed in a feeling of energized focus, full involvement, and enjoyment in the process of the activity. In essence, flow is characterized by complete absorption in what one does.