These are the last lines of his first chapter, and the word doing the work is "Meanwhile." Okakura has just described the modern world shattered in a struggle for wealth and power, waiting for someone to repair the devastation. Then, tea. The world isn't getting repaired this afternoon, and the kettle will boil either way. What he asks you to linger in is "the beautiful foolishness of things," a generous name for whatever doesn't advance anything. The trouble you woke up to will still be there after one cup, so put the kettle on with the news still going and drink the first cup before you turn back to it.
Meanwhile, let us have a sip of tea. The afternoon glow is brightening the bamboos, the fountains are bubbling with delight, the soughing of the pines is heard in our kettle. Let us dream of evanescence, and linger in the beautiful foolishness of things.
Okakura Kakuzo, The Book of Tea (1906), "The Cup of Humanity"