The castle-building habit, the day-dreaming habit - how it grows! what a luxury it becomes; how we fly to its enchantments at every idle moment, how we revel in them, steep our souls in them, intoxicate ourselves with their beguiling fantasies - oh, yes, and how soon and how easily our dream-life and our material life become so intermingled and so fused together that we can't quite tell which is which, anymore.

The Writings of Mark Twain: The $30,000 bequest, and other stories (ed. 1903)