Summertime in pretty much any city is a different experience than any other season, but summer in New York is another world. Many of the people who can afford to escape from Gotham in July, and especially in August, usually do so, and even if their numbers are relatively small among the city's 8 million souls, the extra elbow room that their absence provides the rest of us on the streets, at the museums and in the parks, bars and restaurants lends much of the metropolis a far less frenetic vibe.
“Starting from a concrete, three-dimentional, physical set-up, the preceding discussion produced a rather abstract, multi-dimensional, mathematical idealization that turned out to have an important propriety (namely, the measure-preserving character of the flow). This propriety has other models that are as concrete as the once that led the the abstraction in the first place. Consider, for example, the physical system consisting of a cocktail shaker containing ice and gin into which a few drops of vermouth have been introduced, and suppose that this system is acted upon by the flow induced by a conscientious application of a swizzle-stick. Such examples, of manifest interest, will serve to illuminate several interesting and non trivial theorems, and it makes contact with several of other branches of mathematics (e.g., probability, topological groups, and Hilbert space).”
Paul R. Halmos