From 11:00PM PDT on Friday, July 1 until 5:00AM PDT on Saturday, July 2, the Shmoop engineering elves will be making tweaks and improvements to the site. That means Shmoop will be unavailable for use during that time. Thanks for your patience!
See "What's Up with the Title?" for a full discussion of weight, unbearable lightness, Nietzsche, eternal return, Parmenides, "Einmal ist keinmal." You can also check out "Characters" for details on how these concepts relate to Tomas, Tereza, Sabina, and Franz.